Well it doesn't 'ruin' Windows 7 by any means, but a possible example? IE8.
Alex St. John is basically a troll, but his latest column in Maximum PC hit the nail right on the head for a change - IE8 looks like it was designed with a completely different philosophy than Windows7. Windows7's overall design arch seems to be address the criticisms that past Windows OS's were overly verbose, always "in your face". It has a minamlistic approach that overall I appreciate.
IE8, on the other hand, at least when you first start it up, is obnoxious. It seems as if it came from a different company. Here's what a user who just installed Win7 sees when launching IE8 for the first time:
1) Welcome to IE8 screen. No, you don't start browsing yet - we need a dialog to ask you a few questions first, unlike say - every other browser in existence. You can click "Ask me later", which just delays this to the next time to start IE. So, you click Next.
2) "Turn on Suggested sites"? - Select a yes or no radio button, click Next.
3) "Choose your settings" - choose express, or custom settings. Click Finish.
4) You're then taken to a secondary tab from your default homepage, a Welcome to Internet Explorer 8 page which shows you the features.
So that's 6 mouse clicks before you can start browsing, not counting closing the welcome tab. Recently with the MSN home page upgrade it got worse, now whenever you launch it you're asked if you're looking for the local MSN site, where you have to choose to go to your native home page or always, or ignore it. So 7 clicks minimum and several dialogs/pages to read before you can start browsing.
Sure, once you've done that it's fine, but it really is just tacky and poor design. Google Chrome feels more at home in Win7 than MS's own browser. Not to mention IE8 is so far behind other browsers in the speed department, while Win7 as an OS is pretty damned responsive.
(IE8 when launched was also offered as a download direct from the MSN home page, and came pre-packed with a laughably out of place MSN toolbar, it looked like you just downloaded your browser from a spyware site it was so guady. )
It just speaks to a general lack of design vision throughout the entire organization, and perhaps that's a tad unrealistic goal to have for such a huge company as MS, but you would think they could at least get the desktop experience to be more cohesive, and certainly their mobile division whe they've dug themselves a huge hole. It speaks of a company with many inter-division battles, and this Zune debacle reflects that - some part of the company completely meets their goals, only to have some marketing/sales weenie screw it all up with their idiotic idea of how it should be. How things like this get greenlighted speaks to this - we all know what if this idea were even brought up at a meeting at say, Apple, Jobs would bit their head off. I don't get the impression Ballmer cares enough about the experience at that level, or has enough taste to even know why it shouldn't happen.