I bought myself and the wife an iPhone 3GS so were not locked in, like most the only issue I have is being locked in. Currently in my home area Orange have a crap signal due to overgrown tree's etc but cant get access or rights to clear it - but everywhere else is ok.
If I change network I then get the problem of being locked to them for 18 or 24 months, and who am I kidding thinking they are better than one another
on the iPhone4 though, looks good. I really did hold back but now I have one (business use) it does work pretty well.
Shame it doesnt support UMA ... or does it??