I'm a long time vi/vim user. I don't know that I'd recommend anyone who doesn't already know vi go through the heavy learning curve necessary to become proficient at using vi. There are a number of gui editors which are more easier for new users to learn. However vim (vi improved) is available on very nearly any computing platform you might use. I also find that vim allows me to accomplish some pretty complex editing operations faster than most of my former coworkers using other editors. Having used vi for over 20 years now, I have yet to find an editor which would make me more productive and believe me I've looked. I'm constantly searching for new programming tools in my spare time.
I've been looking for a decent port of vim for the Mac for a while now. The version pointed to by vim.org always seems to lag behind a version or two. It also has a few deficiencies. It used to have screen draw problems and would leave pixel residue behind after scrolling. It also never handled the "-" command line argument properly. This argument causes vim to read its data from stdin which is very handy for piping output from other commands into vim for easier manipulation.
My search is over. The team at Google Code has created a great port of vim for the Mac they call MacVim. It's fast and features none of the problems I'd experienced with other ports. Thanks guys for a great porting job!