Hey, thanks for the feedback!
Yeah you're probably right, I'll lower the chance for those boxes to be trapped in the next version!
As for the serums, there are a couple of ways to safely figure out what they are. There was an item at one point to identify the serums but that becomes pretty useless once you identified all the serums during one run. You have to keep in mind that in the full game one run might be a longer than just those 4 floors. I've also made sure that the negative effects aren't so strong that they can completely ruin your run when consumed at the right time.
As for the Whirlwind and Spells in general. I'm gonna change the description of the spellbooks so that they better describe what upgrading the spell actually does!
And for the ammunition, yeah that's intentional right now. Ranged attacks are very strong and just being able to buy them from the vendor would mess with the balance of the game a lot. I'll definitely think about that some more, though!
Again, thanks for the feedback and thanks for playing!