I'm apprehensive to keep replying to this thread, because of the blind hatred that is almost always accompanied with a painful amount of ignorance... and any comment I make is quickly buried by more blather. Yet, here I am again. I guess I just can't muster the strength to resist correcting wrongs on the internet. Oh well, maybe I'll learn with time.
I read on one of microsoft's developer blogs that the metro start menu is fullscreen primarily because it allows you to visualize what you have access to. It's also finger friendly, and a whole lot better than 7's start menu that is confined to that little box (XP's was better because it allowed the box to expand across the screen). This makes sense. You should be happy that they are making the start menu more efficient, stop whining.
About tiles; a lot of the people in this thread seem to think that the introduction of tiles equals less user control, or dumbing down the system. Where do you get that idea? Adding a UI layer does not dumb down the whole OS, as it does not change anything about it OS; it is an entirely new UI that doesn't really replace any functionality. If you try to argue that the metro UI as replacing the pinnable area in the 7 start menu, then this is much an improvement: the pins update to give you information without you having to open whatever it launches.
I personally hate widgets; I want to use them because I love the idea of getting information on my desktop, but they cover my wallpaper which I like to have a clear view of. Tiles are perfect; no stupid UI or complex themes, no round edges that don't fit together. Information that's nice and neat, that is a separate UI element from the desktop, so my wallpaper isn't covered. I like it.
I have previously mentioned that the biggest reason people hate live tiles is because they don't know how to use them, or how to properly embrace the system. These would be the people who shut their ears and shout nonsense at the first sign of change. It's incredibly annoying, would you stop?
The only valid arguments against tiles are the ones that point out the inefficient text size. Yes, it could stand to get customizable text sizes and perhaps a few tweaks to accommodate more text information (though I can appreciate that the reasons for the limits; this is supposed to be a preview of content, not the entirety of the content, and we shouldn't start asking for entire articles or books to scroll through tile previews). I believe that these updates are coming, however, on both desktop and WP8, so have patience; there is no reason to spew hate on a work in progress, this is only counter productive. One of the reasons I got WP7 was so that I could follow the development of a new technology. It's quite exciting to see something grow and mature
I know that the 360 has a raging preteen fanboy base, but I really don't want to find out that this also applies to Windows desktop. Go bring your fanboyisms to Mac, or linux if you prefer (though I also like to think the *NIX community is populated by professional bearded developers)
Speaking of the 360, I have not heard any mass complaints over the metro UI overhaul. Contrarily, it seems to be positively received almost universally.