I don't understand the hate.... just finished playing it for the first time and I gotta say, I had a pretty good time with it. It's no masterpiece sure but I got a decent amount of enjoyment out of it.
Things that I liked:
The guns were really fun, all the wall running flippy spinny shit you could do with them was awesome.
I really dig Dantes design.
Found the missions fun to blast through, some cool hidden things to find.
The combat, though simple, had some moments of fun.

Things I didn't like:
The ost was pretty forgettable.
The final boss was horrible, and had absolutely no point being there.
The upgrade system wasn't rewarding enough, upgrading weapons didn't feel like it did much of anything.
The other swords were all garbage compared to Rebellion.
The game didn't explain the combat system well enough (specifically combos)
Lucia. What a nothing burger character.
The story was real bad as well.