I have been trawling through free games for my iPod touch. I have had fun with puzzle / turn based games (Undercroft is the favorite so far).

But I am yet to find a platformer / shooter that works for me. Basically I can't control anything that draws a circle and puts arrows in it and pretends it is a joystick. But they keep making them and people give them 5 stars so maybe it is my uncoordinated sausage fingers that is the problem.

Anyone else think that touch screens are bad for twitch gaming? Or can anyone recommend a game where it works?

I've been wanting to post about this for a long time, but in my case from a developer perspective rather than in terms of wanting to find games.

Touchscreen devices are not even close to their button/stick counterparts for twitch gaming in most cases. I don't find it completely unworkable, but it's frustrating. Some SHMUPS opt for full screen input instead of the corner directional inputs, which allows for far more agile dodging, but you obscure your view with your own hand.

When I play a "virtual-DPAD" iOS game, it just makes me feel like it should be on the DS instead where it would be infinitely more enjoyable to control.

That said...interestingly, touchscreen devices are in fact the ONLY portable consoles where "dual-stick" (albeit fake) inputs are actually possible. No device on the market (to my knowledge) has two sticks, so iOS gaming, for those who can handle the virtual-version of "sticks", arguably has that strange advantage. Download Epic Citadel for a decent example but you've probably already seen plenty.

You could argue that the DS can me made to do the same thing, but its screen requires a different type of contact.

I find FPS on PSP quite unplayable. Not even tried DS other than Metroid, which was the same story really.

There's an iOS game that I find particularly baffling called Zenonia. It uses the virtual DPAD not only for gameplay but for all its menus as well - the one thing a touch screen can excel at in terms of in-game UI. I really can't get my head around decisions like that. It just screams of "I DON'T BELONG HERE".

As for your question about games, I don't think you'll find a shooter that gets you around the feeling you don't like.

For the hell of it I'll recommend some games I've played to death though:
Geodefense and Geodefense: Swarm -- awesome and horribly addictive tower defense games, perfect for the device.
Battle for Westnoth -- isometric turn based strategy game.
Fieldrunners -- another great TD game.
Colorbind -- great puzzle game.
Cut the Rope -- great puzzle/physics game.