Are the DLC packages worth it in this game for the added stories/maps/chars? $6.50 seems a little steep for me (after recently purchasing Pokemon X&Y) so I'm playing conservative with my gaming budget at this point. I'm currently somewhere between ch. 20 & 21 so I know I don't have too many chapters left.
Depends on what you're looking for. The packs are separated into two series. For series one, each pack comes with three maps with their own soundtracks (albeit the early ones tend to reuse the same map with different enemy layouts and rewards for completion; mostly because these maps are based on maps from older games; though the music is different for each one (albeit there seems to be a bug that causes the default skirmish music to play instead)). The rewards for these early ones are Spotpass characters (i.e. Avatar reskins) with redone artwork (that's unfortunately rather hit and miss) and some extra rewards like bonus skills and classes (All Stats+2, Paragon, Iote's Shield, and Liimit Breaker, and Dread Fighter and Bride). There's also some stages designed to help you grind up money, lagging characters, or rare weapons. The second series though features largely new content, including challenge maps, extra conversation maps, an extra to the storyline (including its own ending), and Apotheosis which is what all the grinding options are for.
The tl;dr is:
First Pack: Based on FE1/DS1's Chapter 1, you'll fight against (and chat with) the main characters of the series of either gender with allies of the opposite gender and the finale being against both genders.
Champions of Yore 1: DLC Marth (Lodestar Class; Level 8)
Champions of Yore 2: DLC Roy (Mercenary Class; Level 11)
Champions of Yore 3: DLC Micaiah (Dark Mage Class; Level 12) + All Stats +2 Scroll (+2 to all stats sans HP)
Second Pack: Based on the second half of FE4's Prologue, you'll fight against (and chat with) variants of the characters featured in the Spotpass for FEs 1 - 5.
Lost Bloodlines 1: DLC Leif (Trickster Class; Level 1)
Lost Bloodlines 2: DLC Alm (Dread Fighter Class; Level 21) + Dread Scroll (equips Swords, Axes, Tomes, learns Resistance +10 and Aggressor (+10 to attack during user's turn))
Lost Bloodlines 3: DLC Seliph (Swordmaster Class; Level 2) + Paragon Scroll (doubles Exp gains, can stack with Veteran)
Third Pack: Based on the first half of FE7's Final Chapter, you'll fight against (and chat with) variants of the characters featured in the Spotpass for FEs 6 - 10.
Smash Brethren 1: DLC Elincia (Falcon Knight Class; Level 6)
Smash Brethren 2: DLC Eirika (Bride Class; Level 23) + Wedding Bouquet (equips Lances, Bows, Staffs, learns Rally Heart (Rally that provides +2 to all stats sans HP and +1 to Move) and Bond (heals 10 HP to all within 3 tile radius of user at start of turn)
Smash Brethren 3: DLC Lyn (Swordmaster Class; Level 8) + Iote's Shield Scroll (negates Flying weakness)
Fourth Pack: Based on FE9's Chapter 8, you'll fight against (and chat with) variants of everybody featured within Spotpass.
Rogues and Redeemers 1: DLC Ephraim (Great Knight Class; Level 20)
Rogues and Redeemers 2: DLC Celica (Sage Class; Level 20)
Rogues and Redeemers 3: DLC Ike (Hero Class; Level 20) + Limit Breaker Scroll (character's stat caps sans HP are increased by 10)
Grinding Pack: Custom Stages, amusing banter.
The Golden Gaffe: A fuck ton of Gold (on the order of 70000+ if you can collect it all)
EXPonential Growth: Exp piņatas (not that great for maxing out characters but very useful for catching up stragglers and getting around Lunatic's anti grinding features)
Infinite Regalia: Three Random Legendaries + Eldigan (Paladin Class; Level 14) + Silver Card (halves shop prices)
Scramble Pack: Custom Stages, extra conversations between characters who lacked conversations between each other + a fuck load of Event Tiles per stage for extra items, exp, weapon exp, or support points.
Harvest Scramble: Conversations (between characters of the same genders) + a Master Seal + Lissa in a Party Hat
Summer Scramble: Conversations (between first gen characters) + 3 Seeds of Trust + Chrom, Gaius, Cordelia, Tharja, and Sorcerers in swimwear
Hot-Springs Scramble: Conversations (between second gen characters) + 3 Seeds of Trust + Lucina, Severa, Owain, Inigo, and Swordmasters in those Japanese festival robes
Challenge Pack: Custom Stages with enemies harder than the final chapter's, plus an extra reward for fulfilling certain criteria.
Death's Embrace: Dungeon with Spiked Terrain and Healing Tiles (everyone standing on the spikes will have their HP reduced to 1 at the start of the next turn, likewise heal tiles will fully restore anyone standing on them at the same time) + DLC Est (Pegasus Knight Class; Level 5)
Five-Anna Firefight: Five immobile NPC Annas are stuck on a island in the midst of a lava field while a shitload of flying enemies will try to swarm them + DLC Catria (Dark Flier Class; Level 20)
Roster Rescue: Seven Giant Risen are trying to flee, beat them for a Small Bullion each + DLC Palla (Falcon Knight Class; Level 20)
Future Past Pack: Custom Stages that explores a doomed timeline and basically gives the 2nd genners their own little plot arc.
The Future Past 1: Rescue Kjelle, Nah, Cynthia, and Noire + Conversations between them and their parents/alternate selves
The Future Past 2: Rescue Inigo, Brady, Yarne, and Owain + Conversations between them and their parents/alternate selves
The Future Past 3: Help Lucina, Severa, Laurent, Gerome defeat a more powerful Grima + Converations between them and their parents/alternate selves + alternate ending
Apotheosis: Gauntlet against super charged enemies, the game's toughest challenge + a secret route if your team is strong/fast enough + either DLC Katarina (Grandmaster Class; Level 20) or a Supreme Emblem (sells for maxed money). Shit's so ridiculous that enemies will typically sport stats from the 40's to the 80's (for comparison, the highest possible non HP stat cap a PC can sport is 61) and such skills like Dragonskin, Aegis+, Pavise+ and other shitwrecker tier shit. This is pretty much what all that ridiculous crap you've been collecting or eugenicizing is for.
The tl;dr of that tl;dr is that I'd recommend getting the Future Past pack, the Challenge Pack, and Apotheosis for sure, Rogues and Redeemers for Limit Breaker (even though Apotheosis is doable without Limit Breaker, it's practically required for the secret route), Lost Bloodlines for Paragon and Dread Fighter, Smash Brethren 2 for Bride, and maybe Champions of Yore 3 for All Stats +2 and possibly Infinite Regalia for the Silver Card (though you might as well just go for The Golden Gaffe instead since who cares about halving money when you have infinite money). Your mileage will definitely vary on the rest. Iote's Shield and the EXPonential Growth are not worth it, and only Champions of Yore 1 is really worth it for the DLC character since Marth has Good Growths and the stage is easy enough).