I had that question long ago and that made me stick to GEdit and other IDEs. However, when I have to do some works on files in server, I just realise that I have to familiarise myself to command-based editor. And, that's the beginning for me to know vi.
When I open it, the appearance is so boring. No line number, no syntax color. So, I decided to make at least that two things to make vi to be IDE like. Hahaha... Here's what I did:
$ vi ~/.vimrc
then type these lines in vimrc file
set number will add line number on the left part of vi
syntax on will add colour of the syntax
colorscheme desert will set the colour scheme to be "desert"
That's it. I hope I can add some more customization of vi in the future. I feel that I am falling in love for the second time. Oh, vi... I love you.