I felt it was hog, slow, and the interal API is a maze. Also the virtual fs layer ...

It's big and slow, agreed, but it is very powerful. I don't know the details of the virtual FS layer but I can sympathise because that's very difficult to get right in a cross-platform way.

I don't think it's powerful. As fanatic as it seems, emacs is more powerful for real work. It's more human and more theoretical than Eclipse, which is a "usine a gaz" more than anything. It doesn't bring performance, nor ease of use, or stability. I don't get it.

The graphical views are useful, and the wide range of plugins comes in very handy. I could never get on with the emacs interface - it just wasn't discoverable enough - YMMV I guess.

Discoverability in emacs is a tiny bootstrap problem. I have to admit that for years I didn't know how to ask emacs, but when you do (C-h m, C-h k), there's no more discoverability problem.