I'm very successfully using Windows Identity Foundation with Azure AppFabric Access Control Service to authenticate using ADFS v2.
As well as straight authentication, it gives you lots of flexibility over other claims, such as roles (which don't need to be based solely on AD group membership).
In my opinion, its biggest strength is that there is no communication channel required between the Azure platform and your on-premise AD. Everything is done via the browser. From a security perspective, this means that although anyone can reach your application, nobody can authenticate to it unless they can also reach your ADFS server. Access to this can be restricted to on-premise clients only or via VPN, greatly reducing the attack surface.
Also, because ADFS does not need to be exposed externally, it can greatly ease the bureaucratic overhead of deploying it, in my experience.
Only configuration is required, which although it can be a bit of a fiddle initially, is pretty straightforward once you've got to grips with it. You configure WIF to use ACS as it's Identity Provider and create a Relying Party in ACS for the application. Then, you configure ACS to use ADFS as its Identity Provider. You could configure WIF to talk directly to ADFS, but the additional level of abstraction of going via ACS can be useful.
Once you've done your configuration, using the [Authorize] attribute 'just works'.
Note that if you're using Ajax calls into your controllers, you'll need to take some precautions, as Ajax calls don't handle the federated authentication redirect (or the ADFS Shuffle, as I like to call it), but it's nothing that's insurmountable.
All in all, I'm very impressed with the combination of WIF+ACS+ADFS for transparent Windows integrated authentication.