Nokia lumia 800 is one fone i would say can challenge iphone in terms of smoothness. Its really fantastic to use. Better than the overated ,crappyand laggy androids by samsung, htc and all...

Lumia 800 OS might not hv many apps yet, but its interface is one of the best i have seen. Seriously makes those samsung phones look crappy

And dont judge a phone by just the specs, the lumia might be just a single core but it runs better than most dual core phones