I got an HTC Hero this week and love it! Haven't had any problems :)
That said, I don't run many widgets which constantly update. When I was running a lot of widgets some of them slowed the phone down a lot more than others and it feels to me like one or two dodgy widgets could destroy the experience of using this phone.
As I've been very busy recently I've turned off a lot of the things that update constantly on my phone as I found them a distraction. From that angle, I can understand some of the thinking behind the iPhone not having programmes running in the background, though that's a different conversation.