Summarising John Gruber in his post, “Why Windows 8 Is Fundamentally Flawed as a Response to the iPad”:
Apple’s radical notion is that touchscreen personal computers should make severely different tradeoffs than traditional computers — and that you can’t design one system that does it all. Windows 8 is trying to have it all, and I don’t think that can be done. You can’t make something conceptually lightweight if it’s carrying 25 years of Windows baggage.
Jared Newman disagrees by claiming that a Tablet being all-in-one, with both the new Windows 8 interface and the old windows interface integrated, will be more successful:
What Microsoft demonstrated on Wednesday is exactly what I want in a computer — a lightweight tablet UI that’s meant for casual computing and a powerful, classic Windows that allows me to work.
I disagree with Newman on this count as his premise is untenable: “There will be demand for touch-based apps simply because of how many people are already using Windows.”
Just because you are a Windows user does not mean that you will use the new Touch UI add-on as the classic Windows interface is still available. There is a tendency for people to fall back to familiar grounds, despite new improvements that could be had in learning and employing new technology.
Furthermore, why would anyone use the new Touch UI interface when there are hardly any applications written for it? While Newman claims that “Microsoft has proven willing to grow its app ecosystem by paying developers” (as seen in Windows Phone 7), that doesn’t explain why 3rd-party applications on WP7 are still lacking in quality and quantity—What app would you use for GPS running, SSH, VNC, Tweeting, Facebook or Things?
So really, creating an ecosystem isn’t as simple as paying a few developers to port their stuff and leaving a legacy interface behind for “compatibility reasons”. Microsoft hasn’t succeeded, but Apple has. Windows 7 will just be another Windows 7 with its new Touch UI relegated to an “Apple Dashboard-like” position in the OS.