I did levels 2 and 3 while I was at it and I didn't have much trouble, though I did end up dying a couple times. The labyrinth was actually no problem at all. Most of my damage came from arrows I wasn't keeping track of (which was a bit lazy on my part, I'm sure I could get through unscathed if I tried).
Okay, good to know it's doable
For overall gameplay design my main criticism would be that the weapon system seems sort of pointless since I can jump on all the enemies anyway.
This is true for early levels, but later you'll encounter enemies with spikes on which you can't jump, or enemies that fire at you and are out of range, or simply too many enemies at once to fight them only by jumping (in particular when they jump themselves).
Also, instead of having separate keys for every weapon type (which I'll probably never remember), why not just have one "fire" button and use number keys to select between weapons we have ammo for?
And of course: Why is the jump key F instead of space bar?
I think it's more tedious to cycle through the weapons until you get the correct one, especially when you have to react fast.
The key binding is simple: The keys for jumping, rockets, rolling bombs and mines are next to each other on the keyboard (in this order). The more right a key is on the keyboard, the more often you'll use it. By the way, if you don't remember the keys, all currently possible assignments are listed in the pause menu (P key). When using space for jumping, you have to search for the other keys when you need them, while for F they're directly left of it. The F key itself usually has a little "elevation" on it, so you should find it quickly... You're right that space is kind of standard, but do you think it would be more intuitive for Zloxx II? Maybe play a while to experiment with different situations...