For anyone who's never played either Revelations 1 or 2, here's my condensed opinion. They're just my own of course, but hope some may find it helpful.
Revelations 1 is overall an average game with a few good points. It has stronger horror elements than say, Resident Evil 5 or 6, but it's still a bit tame in that regard, and due to being a 3DS game originally the aiming/shooting is a bit simplified as are other mechanics, but it's serviceable. There's a few scenes that stand out and the game has some decent variety in what you're doing, and I think the game ended up having some actually pretty good boss battles for examples (with some good build-up to each even). The game outside of these high points are kind of standard for the series, the ship is never quite as atmospheric as it should be but still a pretty fun location. Less fun is most of the segments where you play as other characters (the game is set-up in an episodic structure, and in each episode you play one segment of the 'main' story as Jill on the ship, and one segment as another character in another time and place), with these locations not being nearly as interesting as the main ship location and a few of them pretty drawn out even. The scanning mechanic ends up being more of a drudgery than anything interesting unfortunately, and the enemies though no bad do lack some extra oomph (and work by some weird mechanics, like shooting their arms to phase them so you can run up and melee them, and can hold the melee button to do a charged melee). The story is fucking ridiculous even by the series standards, and sometimes less in a fun way and more in a bizarre way. Revelations 1 has two of the stupidest 'plot twist' I have ever seen in a video game, they're really bad, but there is some b-charm here and there through it. The music is stupidly good actually with a few stand-out tracks, and the sound design outside of the music is serviceable. Raid Mode, the games bonus mode, is basically dungeon crawler Resident Evil and is pretty fun, probably the best part of the game and has a fun end game challenge to it that you can work towards (and this mode is 2-player online co-op).
Revelations 2 I actually ended up really liking, it surprised me how much I enjoyed it as I was honestly not that excited for it before playing it for whatever reason. For one, the title 'Revelations' applies MUCH stronger to this game than the original game, it has a story that's actually connected to hanging plot threads through the series if you're a series fan, and some things in this title could easily come back in a future entry of the series. The story is also leagues better than Revelations 1... Well correction, the actual story is kind of silly, but it was the first Resident Evil game in ages that actually had a likable cast of characters, and the character drama and interactions between them were both endearing and interesting. Even characters you may initially dislike (like Moira, Barry Burton's daughter with an over-the-top sailor mouth, may grow on you), Natalia is an actually well done child character, and the title made me love Barry Burton finally. Claire I think stood out less but was inoffensive, and some of the side characters were silly but fun. I also think the villain in Revelations 2 was leagues better than the villains in any of the Resident Evil games since the 2010s started up until RE7 released (but the villain is leagues better than RE6's villains or Revelations 1's as example), plus the episodic format has some fun cliffhangers. The gameplay also was really enjoyable for me, with a much stronger item management and survival element playing the game on Veteran my first run (differences in the difficulties as well). This is hard to express, but if you want to be challenged and play with a much stronger survival element in 'survival-horror', I highly recommend it. It has its definite challenge hurdles, but it was a joy tackling things strategically as I went through. The two character dynamic is actually pretty fun, and if you have a way to play local co-op (the main campaign is local co-op only), it can be a lot of fun with another person, but having played it first alone it's plenty fun alone too, the two characters have different abilities and at first the one with the gun seems 'obviously' better, but there's a surprising amount of strategy the second character can employ and if you learn how to use them they can be a bit OP (they also are the better 'exploration' characters due to being able to see items the other can't). I think Revelations 2 gets better as it goes along, with episode 1 being alright, but it getting better as it continues going. There's some memorable boss segments sprinkled throughout, some incredibly fun Resident Evil flavored gameplay bits about, the level design I thought actually was well done (and some fun touches, like things you do in one campaign affecting the other campaign). I could say more, but it ended up really surprising me, it's evident it had a medium budget (but also was released for a medium budget launch price, so that's okay), but it feels like a lot of passion was put in, and benefits for the care put into the design and the story with some of the best quirky elements of the Resident Evil series shining through. The game also has a lot of unlockable modes and stuff when you play through, the one that will catch most people being Raid Mode returns from the original game (and is 2-player local or online co-op, main campaign is local co-op only but Raid Mode supports online), and I could do a long post on it, but while due to a few things I prefer Revelations 1 Raid Mode, Rev2's is still plenty of fun and I think overall is the better game.
My take, hope it helps some.
