I've been messing with the Dell Venue Pro 8, and the Modern UI has impressed me. I recall some discussions about how widgets were useless, but the tiles are very elegant. It makes the iPad UI seem very dated.
It is funny that you posted this topic, because I also bought a Dell Venue 8 Pro last week and have been playing with it quite a bit. I am definitely a fan of Apple, but I am not a fanboy.
Like many of you, I am a fan of technology in general and every fall I buy a couple new tablets to play with. I currently own an Air, a Retina Mini, a Google Nexus 7 and a Dell Venue 8 Pro.
I am finding the Windows 8.1 experience to be much better than I initially thought it would be. I went into the purchase expecting to be underwhelmed, but it has really blown me away. I think that the live updating tiles are a much more elegant implementation of Android's widgets. That is the feature (to me) that makes iOS7 seem quite dated. As an example, I chose the Denver Broncos as a favorite team in the sports app and when I woke up on Sunday, the Sports tile was showing the kickoff time, the opponent and the tv channel, as well as relevant Bronco headlines. Exactly the information that I needed for the day without having to leave the home screen.
Sure, there are some key apps missing from the MS App Store, like Amazon Instant Video, Spotify and Google Docs; however, that is the beauty of the Venue 8 Pro. Because it runs full Windows (plus Office) I can just go to the Desktop mode and use the full-featured versions of those apps.
I think that Apple really was an innovator (obviously) in the tablet segment, but they have grown a bit stagnant as far as re-inventing the way that we interact with our content.
The bottom line, there is no perfect OS. I enjoy using MS 8.1, Android and iOS7 for different purposes. But Apple is stubbornly resisting things (like widgets, etc.) that positively impact the user experience, which makes it much harder each year to justify the premium price.