The Desktop in Windows 8 Release Preview has not yet completely gotten rid of Aero; that will be done in the final version.
That's the upside of the new apps. The downside is that they still seem suited more for than PCs, if you accept the standard definition of a tablet being used to consume content and a PC used to create it. You won't find Office or similar content creation tools among the Metro apps yet, showing yet again that the Metro interface seems designed more for tablets than traditional PCs and laptops.
Still missing is the final form of what the Desktop will look like when the operating system ships later this year. Even though has said that it is and replacing it with a flatter-looking one, that new look has not been implemented in the Release Preview. It is expected to first see the light of day when Windows 8 ships, later this year.
As with the Consumer Preview, Windows 8 Release Preview still feels like two operating systems co-existing somewhat uneasily, rather than a cohesive whole: the visually-oriented and tablet-oriented Metro interface on one side and the old Desktop interface, for more traditional computers, on the other.