The vast amount of bugs is definitely a sign that the Mac OS X team is working on something complicated. Lots of bugs means the build was rushed out, in my opinion.
Leopard is going to be a huge milestone. Heck, they are given until October to complete it. Now that's a lot of time, 2.5 years. They've never spent this much time on any 10.x operating system before.
The new GUI is a placeholder in my opinion, it doesn't match anything and doesn't take advantage of any Core Animation. Something's coming. Hopefully we'll see in June.
As I understand, Apple wants to shame Vista and micro$oft, so this look is not impresive by any means. There must be a lot more behind the curtain.