I´m still going through the game, it´s fun and different which is nice, of course there´s going to be pros and cons, and since it just came out things are going to need to be tweaked so I wouldn´t worry too much over it since it´s such a good concept you have here.
For things i noticed, the level up system is simple and really fits in here, but i couldn´t see any mayor difference after the 2nd gun upgrade.
After I leveled up past level 4 I couldn´t see the effects it had on the character or if spells were stronger or whatever happens.
Maybe pets could have an upgraded version? they do seem like baby pets and having stronger effects would help out a lot, it´s really exploitable.
Last but not least, not sure if you´ll think much of this but, when the living bombs explode, maybe you could make it so the bullets hurt enemies too? since you make them explode i think it´d be a nice little detail to add, but that´s all for that.
I really enjoy your games and I´m happy that you are bringing more to the table :) keep it up and hope you get the greenlight guys.