I feel a lot of the negative review from it is from people that are too egotistic to play on easy, cause they are "real gamers", but would cry playing some of the older roguelikes. This is the old-school style of difficulty, where the choices are "have fun" or "declare yourself a master of the game that wants a challenge".
That said, the game is really good. The jumping did irritate me a little, but that's because it does something VERY few games do these days, and make it so that once airborne, you don't get to control your movement, momentum does, like real life (other than the double jump, that is)
I only ran into two real issues, both near the end.
At the final screen of the gargoyle chase scene, either the game glitched, and didn't spawn distraction monsters like it should have, or the game expects you to jump constantly foreward, turn around and shoot, then turn back around before landing, perfectly every jump to make it stagger till reaching the breakable block.
And secondly, at the very end of the final fight, I had to restart cause the npc you were supposed to stand next to near the boss to do a thing with derped out and was stuck walking right into the far wall.
I will agree the naga-wolf boss is extremly tedious to fight, unless you toss and hit with all the floor mats (which block the fireballs from above, and do a lot of damage), before they can break in the chaos of the battle.
The bow is actually the ultimate cheese weapon for most fights. if you draw back the string, and release it the instant you hear a tiny chime sound it launches an explosive arrow that does stupid amounts of damage, without any shot limit other than skill in timing.
For the levels, go with the whip-thing if you can in most instances, it does huge damage, attacks very fast, and can easily be used while jumping to wreck face. just be absolutely sure to swap to the card or bow before fighting bosses, as bosses seem to have some sort of invincibility frames, and often limited locations to deal damage (the naga-wolf only seems to be hurt if you attack her upper half, for example).
Edit: the axe is pretty meh for everything other than cheesing enemies through floors/roofs, and the boulder is almost more of a trap than help. It's super slow to use and can hurt you if you aren't careful. ...it can be fun in some places though. And the card/seal weapon seems to be what most the game is balanced around. Nothing fancy, but no real drawbacks either.