I don't love or hate Windows Phone 8.1, but in its current state I would not buy a Windows phone. The tiles are still too plain, ugly, flat and square (no depth), and the graphics on them are very simplified and bright white which is hard on the eyes. And this applies even whilst just looking at a screenshot of a Windows Phone Start screen. That's not my taste. Anybody remember Jenga? I'm not loving or hating the tile thing, but I would be open to giving Windows Phone a go if certain requirements were met and obviously they most likely won't, so it's a no sale for me and I'll explain why later.
The Start screen's default color scheme is really bad, and Microsoft needs to spruce things up if they want it to catch people's eye. If you look at the screen shot below, you'll see that the Start screen looks very ugly, plain, and worse than the graphics in Windows 3.1:
If we look at another photo where a background image is being used across all tiles things look a lot better, but still, I don't like the font color and second-rate, uninspiring images on the tiles:
Another problem is branding. "Windows" is not a cool thing with hipsters and the whole small device "Look at me I'm cool because I have a cool phone that spies on me" movement. Windows means Office, Exchange, PC games, and running business applications to most. It also means malware, spyware, crapware, ransomware, insecuirty, Windows rot, and more negative things. Can we say the Windows brand name is tarnished, even though it's widely known? Just because people are hooked on Windows for one reason or another, doesn't mean they love Windows and are going to go out and buy a Windows phone when they had a perfect opportunity to get away from Windows. Doesn't Microsoft understand? I guess not! People aren't associating it with something being in the the same category as an iPhone, at least from what I've seen. My advice would be to come up with a new name instead of Windows. How about Lumia OS? Lumia's already known, and it sounds good and would be an easy transition for consumers. For me to buy a Windows phone, the source would need to be opened to prove there are no backdoors, and I will never use a device with a built-in kill switch/backdoor to "protect" me. These things I desire obviously most likely aren't going to happen, so I'll stick with the open source CyanogenMod OS and rooted Android phone I own which has been serving me wonderfully.
Nadella is leading a company that had 142.43 billion in total assets last year, and while the layoffs are a good first move, I'm not yet convinced that Mr. Nadella is going to last in a culture of corporate bureaucracy and a board which seems to be clueless. Just because Nadella has a vision, doesn't mean squat. Sinofsky had visions and look where that took Microsoft.