I've mixed feelings. I think, overall, I'm a bit disappointed. It's not a bad game by any means, it's certainly very good, it's just not exactly what I was hoping for.
I prefer the atmospheric and more subtle storytelling of Nocturne, which felt like the story was created as catered to my tastes exactly, or even SJ; I prefer the story and story direction of SMT2. From a gameplay perspective I think IV is definitely smoothest, however, I absolutely abhor Smirks and I feel like the battle system in general needed a few more weeks/months of smoothing and rebalancing. You can beat almost every late-game boss with one ability; Party MP walk is so utterly broken that any self-restraint is pointless. And, as mentioned, I feel like the change from HP to MP for physical abilities seems very strange.
And no, I don't think there's an escape route. You'll get an App ability later that stops you from having MP issues, though.
That said, and these are pretty major story spoilers:
That entire duo of apocalypse sections after the first time you side with Walter/Jonathan was pretty amazing.
I was silently squealing in joy the entire time.