Windows Phone 7 could be amazing. It's not, yet. Right now, it's a good start. This is what's broken, and what Microsoft has to do to make it truly awesome.
1. Multitasking for third-party apps—or at least fix the damn resume time
Windows Phone 7 doesn't have multitasking for third-party apps, even though every other major smartphone OS out there does. That's already borderline unacceptable for some people, but what made it nearly tolerable on the iPhone was relatively quick app launches, persistently saved data and fast resumes.
So far, the bag is mixed. If you lock the phone and immediately unlock it, with most apps right now, you'll be hit by a Windows Phone "resuming..." screen, and then you'll often have to wait for the whole goddamn app to reload, whether it's Twitter or a game that took you a minute to get going in the first place (Rocket Riot, I'm looking at you).
The most obvious, best solution is to get multitasking for third-party apps onto the phone as fast as possible, using a model like iOS 4's limited multitasking. In the meantime, app load times need to get faster, and resuming apps needs to take less time than my grandfather's funeral. This is possible, and it's in app developers' hands to fix it. "It's primarily an implementation thing," says Windows Phone's Greg Sullivan, though he's quick to say the blame "is still on us" for not providing the right guidance for developers on how to come back from "tombstoning," which is Microsoft's fun word for app going dormant.