I have mixed feelings on Revelations. First, let's get out of the way the fact that it was originally conceived for a portable system, and being what it is, it's not so bad, but it makes it harder to compare to regular entries on the series (for example, on my opinion, it's inferior to RE5 and especially RE6, which I actually rate higher than 5.).
That being said, I'll start with the things I like it: The game is pretty. Even on the 3ds it was pretty, and when I got it for my PS3 I really enjoyed the graphics and the atmosphere of the Queen Zenobia (not so much on the other set pieces though). On a sense, it's graphically very similar to Revelations 2, which was conceived for regular consoles (damn...Revelations 2 really had a lame budget...). The game plays well. Similar to RE4, but you can walk and aim. The dodge system is...clumsy, but it kinda works and the partner A.I doesn't get in your way. It's okay. Raid mode is nice, actually better than Mercenaries in some instances.
Now, for the things I didn't liked it: Story is garbage. It's a convoluted mess of a plot, with badly written dialogue. It also have horrible, horrible characters. Jill has the characterization of a door, Parker is okay-ish, same as O'Brien. Chris is pretty much okay, he's same old Chris, and Roger Craig Smith does a better job than anyone in this game. Raymond is a crappy character with a crappy haircut, Jessica is annoying and Rachael is just a walking anime fan-service. Quint and Keith are equally annoying. The plot is totally irrelevant to the series as a whole and I doubt we'll see the G-Abyss back in the series (or even Revelations original characters, for that matter, except for Parker in a mangá so...not much). Enemy design is very uninspired too and most of them are "meh" to me. The hunters are also a disappointment, since they're an enemy you're supposed to fear, but it's kinda hard to fear them when you fight packs of three or four at the same time, dropping them easily with even a damn handgun. The Genesis is a gimmick that makes the game way too easier, because every damn room has two or three secret ammo pickups. I normally play without using the Genesis to scan for itens. Only enemies and story related bits, to make the game a little harder, because it forces me to cycle through my weapons and to have some strategy involved.
In the end, it plays okay, it's easy on the eyes, but it has some crappy plot with annoying characters.