I haven't done all that much with Java for reasons that will quickly become apparent, but the basic idea and syntax rocks my world. An OO language that actually makes sense and doesn't have layer upon layer of glued-on cruft (*cough* C++ *cough*)? Great!
What I don't understand is why Sun went to the trouble of designing an implementing a nice language on a bunch of platforms (certainly a non-trivial task) and then screwed it up by not making their APIs truly object-oriented. I don't claim to be the world's best programmer, but writing non-OO core APIs for an OO language (especially one that purports to not suck like most of its ancestors) is dumb.
A fundamental concept of object-oriented programming is that you tell objects to do things without worrying about how it gets done—a concept that Sun violates frequently by making programmers deal with implementation details.
If a SQL statements needs to be prepared before being executed, why do I have to take care of it? Just do it! Don't make me type connection.prepareStatement() every time I need something from the database!
Even having to know of the existance of javax.swing.JFrame.pack() is inexcusable. If the frame needs to be packed, pack the damn thing and leave me out of it. This is [ostensibly] OO! Why should this be my problem?
Why do servlet programmers need to deal with doGet(), doPost(), and doPut()? Not only is this bad OO design (how about behaving like an object and giving programmers access to passed data in the same way regardless of how it was passed?) with very annoying results (more typing and enforced nonsensical code), but it's brittle: what happens when additional methods get added to HTTP and the interface changes? Is everyone going to have to go back and add doBlah() methods to code that already works? How much is that going to cost the Java community in time and money?
When programming, I try to take a "when in Rome" attitude and abide by the conventions of the language and methodology I'm using, and that's as it should be—it would just be nice if Sun did, too.