"Well for a start, things default to a set of groups that do have a rationale behind them."
Wrong. Things that *Microsoft already knows about,* such as Office, do so. Most of the programs I have installed, which are *not* Microsoft products do not default to any sort of rational order. Also, it may be an infrequent operation, but it's a crappy implementation, and it ensures that I spend as little time in the Start screen as I can humanly manage.
"The Start Screen on my Desktop easily accomodates fifty programs and with column spacing between groups, it's very easy to know immediately where they are."
That's great if I want to visually sort through 50 totally disorganized icons to find the one that I want. Again, I don't spread fifty different folders across my desk so that I can pull the one out that I want; I have them filed and organized so that I can locate them. Also, why can't I grab a bunch of tiles at once and relocate them? Why do I have to pick through each tile of dozens and relocate it? That's poor UI design, and I defy you to argue otherwise.
"You can still type and search."
That much is true, and it is faster on Windows 8, so kudos for that.
"Not all programs are placed on the main Start Screen. You have to go into extended mode with an extra click to see all installed programs."
That's true. All the useless crap that Microsoft wants me to see, like Shopping and Weather, are on the main screen by default. Things that I might want to use, like the Command Prompt or Control Panel, are hidden away. But, typically, when a program is installed, it puts itself on the main screen in some totally arbitrary location.
"With Win7, many people end up with program shortcuts all over their Desktop. In Win8, it's far more likely to be clean and free because program start icons all go onto the Start Screen."
Again, wrong. I have put *more* stuff on my desktop and taskbar so that I don't have to use the Start screen, and I even wind up using the command line more frequently.
Anyway, I'm glad that Metro works for you. For the majority of desktop users, I suspect it's at best a useless change and at worst a significant impediment to productivity.
Actually, the funny part is that the "tiles" UI bears the greatest resemblance to the Lotus Notes desktop, an interface which is devoutly loved by a few fanatical fanboys and loathed by the majority of users.