I think that's a bit strong. There are bits of the standard library that are fine - collections, concurrency, and anything else designed by Doug Lea. I even get on fine with IO and most of networking. Sure, Guava adds a lot of really nice stuff to collections, but it adds rather than replaces.

Then there are bits which should be avoided at all costs. Date and time is one. All the GUI libraries are another. HTTP via URLConnection isn't terrible, but people mostly use Apache HttpClient instead. NIO is a mixed bag, with some really good bits, and some complexity whose necessity escapes me (particularly since it can be hidden by XNIO without losing anything).

It is a real shame that there is this patchiness. I would love to claim that all the rough code is from the pre-1.2 era, but i would be lying. Particularly if you look beyond the JDK and into the enterprise libraries, there have been some real shitshows given official imprimatur (i remember Java Advanced Imaging being particularly horrifying).