Better then you'd expect most likely but tbh its not everyone slice of pie if you can id suggest going to a local store with working ones and use it if you like at all buy its becuz mango is going to be amazing and wp7 will only grow stronger from there
WP7 is good, I myself find the Arrive to be an ugly phone with no redeeming qualities but it's owners love it. ( Probably because Sprint phones sucks anyway )
The software is awesome, is fast, smooth, lacks bugs and most importantly is fun to use =)