Don't use the same type of UI element for two different things (health bar and ability cooldown)
True, it's a lazy meme UI. Down the line I anticipate having multiple abilities so those will probably migrate down to WoW style cooldown icons.
Not a fan of the wave-based gameplay.
You and me both pal! This isn't my 'grand vision' for the game, it's just the bare minimum to provide a gameplay objective. This is basically the prototype stage at this point. Better (or any) AI is a big future goal.
[Bats] don't have to actively think about flapping their wings just like people don't have to think about moving their legs
This one I gotta push back on. Yes if I'm running on a flat surface then I don't think about moving my legs. But what if I'm running on a trail in the woods? Then I'm making sure I don't trip on roots, I'm stepping over rocks and logs and ruts. It's not 100% of my focus but I have to notice it and adapt. I think that's probably what it's like if a bat is flying and chasing down a bug. So I'll defend having a "flap" button.
But overall I do agree the flying isn't as bat-like as I would like it. I tried to get something more in that vein but it's tough to get the camera right if the player is raising and lowering their elevation like a bat flits around in the sky. Also it was tough to base the acceleration/velocity on flapping action rather than a constant 'forward' velocity. I think it's fun to fly right now but I hope to make it more distinctive in the future.