Honestly tough to answer this. It's one of those things where you just have to use it for a while to realize how supportive it is of programming. All of the bundles (mostly developed by third parties) certainly helps. You can basically automate/script the application any way you like. There are bundles for different frameworks/libraries that can speed up common development tasks.

But is it better than Eclipse in terms of sophisticated language support? For a dynamic language, maybe that's not so important. But for a verbose statically typed language such as Java, it's critical.

BTW, if you have not checked out Eclipse lately, see:

http://download.eclipse.org/eclipse/downloads/drops/R-3.2-200606291905/new_noteworthy/eclipse-news-all.html

I don't see it as a tool which can be compared easily. Eclipse (in my view) is more of a complete IDE. Same with Visual Studio (also superb).

Textmate is a seemingly minimalist programmer's editor. When you get into it and start hacking you start to see how much is really there. Definitely not an IDE though.

Compared to eclipse: Bloat.

Why does it matter if eclipse is huge? Your productivity is what's important. And for Java, eclipse results in a dramatic improvement in productivity.