I've only played HoMM3, although 2 and 3 are pretty similar, and 1 really isn't that different either, so... let's just say I'm mostly acquainted with the pre-4 gameplay style, but I'm most familiar with HoMM3.
I DO like HoMM3, but I have a lot of issues with it.
- Resources. The game has like, seven resources. The problem is that for the most part, gold is the only one that remains useful throughout the game. For town building, MOST buildings use wood, but it's not a lot. Some of them use other resources, like ore or sulfur, but again, that's only one or two buildings per town and still a pretty small amount of it. And the only creatures that tend to use resources other than gold are like, the top-tier ones. The only thing that DOES require a good amount of special resources is the Mage's Guild.
So for the most part, resource control really doesn't matter after the early part of a mission, which is a shame because there are a lot of resource points on the map and you can reinforce them and stuff (Or you could in the expansions, at least). But... none of that really matters. You CAN sell them for gold via the Marketplace, but that sort of calls into question why even HAVE a bunch of resources if you're just going to convert most of them into gold anyway.
- Unit diversity. The units are actually pretty diverse. Outside of the basic units, they all tend to have special skills. Downside is that there's also a very clear and linear increase in terms of power, so it *tends* to be the case that a really strong unit is going to be superior to a weaker unit even if the weaker unit has an interesting special skill. Which isn't really good design.
- Going off the former, and this is worse, is the whole giantest-stack-beats-all thing. So to a big extent numbers of units are more important than what units you use. Having a balanced party really doesn't matter unless you start getting into missions where you can combine units of different races, since the game is set up in a way that you usually end up having a party consisting of the highest amount of all the upgraded units that you can build (You have seven army slots, every town can build seven different creature types, etc). Again, not much point in having a balanced army.
- Upgrading was kind of linear, both in terms of towns and your creatures. This actually isn't a huge deal in itself outside of doing the same upgrade tree every mission gets boring. Similar this is why I don't like most RTSes and why a lot of city building in 4xs bugs me. You always end up sort of doing the same thing every time, and especially with the 4xes, you're never really forced to specialize. There are games that address these problems -- base building in Dawn of War: Dark Crusade is fast and bases carry over between missions anyway, so it's okay. Civ 4's inefficiency stuff makes specialization a better idea. Anacreon was completely BASED on this idea -- but still.
- Finally, the combat. I'm not sure how much being able to move your troops around in combat mattered. In terms of the hexed-base nature of things, yeah, you had some area affect stuff, and units having varying move distances or being able to move twice was also a nice touch, but... It felt off. Maneuvering for the most part didn't matter since terrain obstacles, with the exception of castle sieges, were few and irrelevant. So it's just like, move all your guys to the left, other guy moves all of his guys to the right, line up in the middle, and fight.
- This is really minor but I don't like games capping the amount of heroes you can take between missions. I think a better solution is to just let you take all of your heroes over and reduce the number of heroes you're allowed to use in the preceding mission. So like, instead of letting the player raise ten heroes but only transfer four? Just let them only have four heroes. Because you're generally not going to raise more than four heroes anyway if you can't transfer them. Exception being if you want some guy to just lead an army to defend some random junk, but in that case I think you should allow for heroless armies or non-hero generals or something. IDK.
- What is problematic for HoMM3 is that the campaigns are only like 3-5 missions long whereas in HoMM2 the campaign was like 10 missions long, so the time you get to spend with your heroes is limited which is sad.
What I did like?
- HoMM3 has the best hero system I've ever seen in this type of game, hands down. The amount of equipment and skills and ways of building your heroes is pretty hefty, and it all matters a lot. I seem to recall all the spells being interesting and useful (Even the ones that added terrain hazards. This is sort of the OTHER exception to my point above although the downside is that they still only really matter much in sieges, so...). Also you were limited to the number of skills your heroes could take too, meaning you had to make non-linear, interesting choices about how to specialize them.
- Map features and interactivity. I wish it wasn't the case, honestly, but there hasn't been another Hero-styled game, from what I've seen (If there are exceptions, please! Tell me!) that have as many THINGS on the map. Lookout towers, portals, huts, artifacts, little find-the-item quests, leprechaun circles, buildings with treasure and stuff to recruit... The maps were insanely detailed and it was wonderful.
- Random map generator. This is from one of the expansions, but it worked really well and sometimes even led to more interesting scenarios then some of the hand made ones. Partially because of all the map features interacting in interesting ways.
- Exploration was also super-awesome because there was always new stuff to find. There was never a lot of dead-space in the missions.
Other games implemented stuff better but still had problems. Some comparisons...
Disciples 2 - This is probably the second best after heroes in terms of interesting maps. The missions also have a lot of scripted bits which is cool.
The biggest change is the combat. You only have 6 units to a side, at most, and combat is more... JRPGish. What's different is that every unit is VERY unique, so party composition is super important and numbers don't matter at all.
Second, you have multiple upgrade branches for your units. So, for instance, your basic healer unit can either be upgraded to heal more damage on one unit, or heal all units for fewer hitpoints. And you can only pick one upgrade branch per mission, which is a really neat touch and forces you to strategize.
Third, resources. The game has five resources -- gold, and then four colors of mana. Gold is used for buying and building. Mana is used for spells, obviously. What's interesting is that each race only really uses ONE kind of mana. So you might be in a situation where you mostly have green spells with one or two white spells, but you still want to control the red mana because your enemy is predominately red and if YOU control the red mana, your enemies can't do anything.
Major downsides, though?
There's two. First, the game is kind of grindy. Unlike Heroes you don't pay to have your units upgraded. They have to gain exp in combat. You also tend to get a lot of heroes going in a single mission since there's like... five classes, I think, and they're all REALLY heavily specialized. So, a lot of time is spent figuring out which monsters are weak enough for them to beat and sending them after said monsters to get their rank up. And you spend a lot of time doing this.
That wouldn't be much of a problem in and of itself but the second problem sort of... worsens it. You can't carry much over between missions. ONE hero -- and, as I said, you have a lot of heroes in a mission -- can transfer. Only one. I think you might be able to take a handful of items and one or two other units from you heroes army, but basically you spend a loooot of time building up level one units and heroes.
I'm going to talk about Lords of Magic: SE and Warlords 3 in another post. Probably not Kohan since that's not really that similar to HoMM-style games.
I won't be talking about Master of Magic, Elemental, the Age of Wonders games, or King's Bounty, since I don't know a lot about them (Although I played AoW2 briefly a million years ago and it looked neat. They're getting digital re-releases sometime soonish so I'll give them another shot then).