It's not that it's mean, it's that it's content-free. If I wrote "I think the Windows Phone 7 UI looks cool and the rotation effects are awesome" then I hope you would downvote it, because that is a trashy comment. (The real comment in question had 4 more lines, but they were all equally vapid.)

You have a specific comment about some identifiable aspect of the rotation effects? OK. You have evidence that the new wave of Zune-ish Windows UI style is not popular? Neat. You want to compare some design decisions between the WP7 UI and the iPhone or Android UIs? Sure, go for it. But if you have nothing to say, why say it?