The stock Moto UI is laggy and sluggish. When using Launcher Pro however, its smooth an quick. It all depends on the UI your using. I wish Motor would have better tested their UI before releasing it because it just doesnt feel all that great to be honest. And, now that Im hearing reports that froyo is actually making the device slower... Yeah, glad I returned mine. I loved the size of the device and how solid it felt(loved the druid 1 build also) and was fun going on websites due to the shear size, but the battery life and stock UI just ruined it. However when I did go to return mine at the store, I messed around with the floor model and the UI on theirs did seem more snappy then mine. So, it might just be the luck of the draw with the phone you get. Mine unfortunately seemed to be the worse of the bunch.
Ill wait an see what updates bring to the device before I go back and purchase it again.