I'm with Stu on this. My DS and other consoles have had almost no 'game time' at all since I got my iPhone. And although there are several games I really like for that system, games for Apple handhelds just take up too much of my time (in a good way).
Flight Control alone has taken many hours of my life, and now Stu—no doubt while laughing maniacally—introduced me to Drop7... (As for, 'you get what you pay for', 59p for Flight Control is the rough equivalent of going into Sainsbury's and coming out with a trolley load of tasty food for a fiver. Far too many DS and PSP games are like nipping into the same shop with a crisp 50-pound note, and leaving with a pile of glossy fruit that goes off surprisingly quickly.)
While I'd say there's definitely—on average—more immediacy with games for the platform, that doesn't necessarily tally with a lack of depth, nor with something that's only worth quick blasts (although there are far more games in the 'quickfire' category than for any other system, but that, for me, is also a bonus).
As for 'jerky controls', I'm not really sure what to say there. Aside from games that try to emulate other systems (Nicky Boom *shudder*), most of the best—Blue Defense, Drop 7, Flight Control, Cube Runner, Dropship, PapiJump Land, Galcon, Rolando 2, Saucelifter, and so on—are silky smooth. If you get jerky gameplay, that's probably a RAM issue, and pretty much every iPhone/iPod touch dev recommends a device restart after installing software (or if performance starts to stutter after extended use).