I'm inclined to see the fuzzy nature of both Hubs and of the OS integration of online services as something of a negative -- particularly in business environments and for non-power users. There's a lot of room for confusion, though I can see that Microsoft was arguably going for flexibility.
App selection and development
Apple wins. No contest. Despite the number of developers who have downloaded software development kits from Microsoft, iOS has a two-year head start on Windows Phone 7 when it comes to app development, and there's a wealth of games and virtually every other kind of app imaginable already available in Apple's App Store. The app development process for iOS is also well documented, and there are tons of resources for iOS developers, including Apple's documentation, books, Web resources, training classes and thriving developer communities.
Microsoft will probably get to a similar ecosystem eventually, but being late to the app party could hurt WP7 in the short term. Fandango found the WP7 development process easy to work within, ranking it similar to Apple's Xcode. And Microsoft has decades of experience creating developer tools and communicating their use. But for now, Apple has a clear advantage here.
Music and media: iTunes vs. Zune
Another area where Apple has an advantage involves music and other media. The iTunes Store is still the biggest online music retailer, and Apple has made iTunes and iOS integration very strong, building on the success of the iPod. Microsoft didn't have nearly that level of success with the Zune as a media player or as an online music/media store. That said, Microsoft does offer support for a decent range of formats from both the Zune store and other online retailers, including Amazon.
Microsoft does have an advantage in terms of the monthly subscription feature known as the Zune Pass. Apple has argued that people want to own their music, not rent it, and that's true for a lot of people. But if a catalog is big enough, and you primarily listen to music on a mobile device or PC, then a subscription service can be an attractive option.
It's a close call, but Apple's iTunes integration in iOS gives it a leg up -- for now.
Game Center vs. Xbox Live
Apple only recently stepped into the multiplayer online gaming arena with the rollout of Game Center in iOS 4.1. Game Center is available to both the iPhone and the iPad, which offers a larger format, and therefore a richer, gaming experience than the iPhone. While Game Center already has a fan base of users, it's relatively new, not all iOS games support it and it's limited to mobile gaming.
Microsoft's Xbox Live is mature, has an installed user base of more than 20 million, offers more features and lets you connect from Xboxes as well as mobile phones. This means that if you're serious about gaming (at home or on the go) and own an Xbox, WP7 is likely to appeal to you as a mobile gaming solution more than the iPhone or iPad.
The real question of who has the mobile gaming advantage will come down to who has the games people really want to play. With limited knowledge of what's coming to WP7, it's impossible to answer that question right now. But it's clear that Microsoft has a significant stake in multiplayer online gaming and has been working with game developers like Electronic Arts (EA) to ensure that WP7 will have serious gaming choices available.
Office, SharePoint and Exchange
Microsoft wins hands-down when it comes to Office apps and integration with SharePoint and Exchange. Yes, iOS has Exchange support built in, but there have always been issues with integration that depend on the Exchange infrastructure in place. By virtue of being developed alongside Exchange, any Windows device -- PC or phone -- is going to have the advantage over anything else, including iPhones and iPads, Android devices and BlackBerries. And access to SharePoint is almost certainly going to surpass any third-party offerings that are out there for iOS.
I also expect a mobile version of Office to generally have better feature compatibility with Office documents than a third-party app. Whether mobile Office is better as a suite than apps like QuickOffice or Documents to Go is less certain.
Advantage: WP7.