You have almost everything VIM is awesome at + nicer non terminal based UI niceties. Plus its really really fast. You get the code wall, really good window manager, better project management and its also cross platform.
Gvim has a lot of awkward hangups, in my opinion. Selecting text is still weird, there's no context menu, etc. It's vim outside of a terminal, which is great, but most full-fledged graphical editors take better advantage of their environment than Gvim does.
I agree with gvim being a bit basic. If you're on OSX, I think MacVim (http://code.google.com/p/macvim/) is a much better choice. On Linux, I use terminal vim and rely on the terminal for environmental integration: you can choose from a dozen X terminals that will do almost anything you want.