I've been playing a lot and it's real fun. I've never been able to get past 13, but even still it's fun to stack up runics and go wild.
Like others have said, the UI gets in the way but it's pretty easy to get rid of it by zooming. Something that annoys me is how sometimes there will be a particularly deadly enemy behind a door and I get killed immediately; it's almost like I have to be scared of doors to not be killed by a death mage or a dragon waiting behind. Also, apparently rats seem to know where you are at all times, and that's nonsensical. It's also really annoying, as they waste my time and chip away at my health, Another weird thing is how loot tends to peter out after the first few floors—I'd think it'd be more common the deeper you go. Though, it does reinforce the fact that you need to get a good build and stick to it. Another thing is how Force damage when crashing into something is with distance, and not the power of the Force runic. I'd think that, as more powerful Force runics can push something farther, that must mean that the thing is going faster, and therefore should have more damage be done.
I've found that, occasionally, using a teleport spell will clip you into an enemy and render you weirdly invulnerable while you control the enemy, and sometimes after coming out of water the enemies stop making any moves of any kind. Also, you can push barrels into enemies. Additionally, pressing 'q' at the starting screen makes every button black. Also, the runic system would really benefit from a rework into a more balanced relationship between spell and item runics. The ranged properties of the spells, the fact that they always proc, and that they are usually more powerful than item runics makes them a bit more useful than item runics.
Regardless, the game is very fun and I'll be playing this for a while.