As much as I want to like how Microsoft has altered the aero ui in Windows 8, I just can't. From my perspective, aero (glossy) and metro (flat) just don't mix. If they're going to go simple, why not keep it simple? A glossy/flat crossover doesn't work as well as one or the other. W7 aero works because they went glossy the whole way. W8 metro could work if they went flat the whole way with transparency. From what I've seen so far, they've tried to make transparency = gloss, and it simply doesn't work.
Long story short, you can expect a metro ui theme with transparency from me soon.