The phone is very responsive, I might even go as far to say that it performs better than my Stock Eris.

 

I played with the Ally and it is a very capable phone. I don't think it's a power users phone by any means though. It has some lag at times (like the Eris), but it is a nice midrange device. It's a good alternative to the Eris for those that want a physical keyboard, but don't want to pay the extra price for the Moto Droid.