I'm really digging this game. I think it is my favorite game
of this type since the DS Castlevanias. I buy pretty much every Metroidvania that comes out, always hoping to find the next one the grabs me—Guacamelee, Ori, Hollow Knight, Axiom Verge—but they just never seem to scratch the itch and I end up dropping them almost immediately. Now it could be because it is such a joy to play anything on the Vita, but I'm already 40% through Chasm, and as soon as I finish writing this I'll probably put in another 10%.
The graphics and overall style really work for me. I couldn't get in to Hollow Knight because I just didn't like how it looked. Chasm has the pixel art style that really appeals to me, and the monsters are really well designed—quite similar to Castlevania enemies. I kind of wished they had take even more from Castlevania's playbook and added some sort of "soul system." I like just running around killing stuff, but there seems to be little incentive to do that (I'm still relatively early so maybe that will change).
I also really like the sub-weapon system, though I feel they are almost too powerful. In Castlevania, I tend to use sub-weapons sparingly, but in Chasm I've been integrating them as a regular (and essential) part of my attack.
Overall, if you are looking for a Metroidvania style game that is more stylistically similar to the Castlevania games, I'd definitely recommend this based off of the time I've spent on it so far. I'm not going to say it is better than the other games I've cited here, but I can say with certainty that I personally like it a lot more than any of those games.