If you are just looking to get back the Aero interface, all you have to do is change 1 registry key.
go to...
HKEY_CURRENT_USER\Software\Mic rosoft\Windows\CurrentVersion\ Explorer
In the right pane, double-click on RPEnabled key and change its value from 1 to 0.
(from
http://www.dedoimedo.com/computers/windows-8-metro.html )
As that site notes, it was done on the developer preview version, but i talked to a buddy last week who mentioned doing this tweak, so it should still work.
Pros: Free, improves speed a bit.
Cons: Lose a few of the new Win8 functionality.
I don't have Win8, so I haven't used Start8, but it looks nice, for only 5 bucks. Gives you the start menu option, and can switch to the win8 metro interface on the fly.