Nice visuals and voice effects, I felt the game was relatively fast paced, which for me, contributed to the fun of it. The gravity system is smooth but slightly confusing and indeed adds unexpectedness (even though clearly not the main unexpected factor) initially.
Unexpectedness factor is fairly present once weapons are switched.
A bit hard to move around due to so many blocks getting in the way, very fast moving enemies, and having to think what button to use in order to jump or move in the right direction depending on how the gravity is pulling you. Still, these things aren't necesarily bad, just a hinderance that makes it slightly complicated when playing for the first time.
By far the most confusing thing I noticed was the tiles changing texture (I'm guessing it's that dimension anomaly thing)? Also I'm fairly certain I got teleported to somewhere random at some point. Either that, or I died without noticing or was just confused by tiles changing texture. No lag for me, but after the 3rd texture change, the game crashed on browser.