Long time Textmate user here. I'm learning emacs because of the productivity and the portability.
I tried vim but gave up, the Esc key was too clunky to me. Then I tried emacs and it was way more bearable. To be sure, I still need to figure out the features other than moving the cursor around but...all in good time.
Undo button is a bit weird conceptually. When does it switch to redo?
Yeah, the undo is a bit strange -- in stock Emacs you have to make a change to the buffer to start undoing in the opposite direction. You can use "undo-only" for a simpler model, or check out some extensions that modify undo mode: http://www.emacswiki.org/emacs/CategoryUndo.
The cool thing about Emacs undo is that it can undo in a region. So, say you've made a bunch of changes, and then realized that one of your earlier changes to a particular line were incorrect: just highlight the line and then undo within that.
It switches back to "undo the last undo" (since it's always "undo the last buffer change") when you break the chain of undo, i.e with C-f or a similar non-destructive command (like movement). See: http://www.gnu.org/s/libtool/manual/emacs/Undo.html
Funny. I tried Emacs a few times but it was always that undo thing that kept me from sticking with it. Incidentally, it was also the undo that kept me from sticking with Textmate. At some point, I settled with Vim though. Lots more strangeness there, but at least undo works.
I agree that Esc is clunky, but most people don't know that ctrl-c has the same behavior. If you remap your caps-lock key to ctrl, it's a very natural keystroke (at least for me) where you don't need to leave the home row.
I tried vim but gave up, the Esc key was too clunky to me. Then I tried emacs and it was way more bearable. To be sure, I still need to figure out the features other than moving the cursor around but...all in good time.
Undo button is a bit weird conceptually. When does it switch to redo?