The main features of VIM and improvements of VIM over
vi:
- VIM is 99% Vi compatible
- portability
- multi level undo/redo
- multiple modified buffers
- Graphical User Interface (GUI) mode
- split windows both horizontal and vertical
- syntax highlighting for hundreds of file types
- trans-session history of commands/searches/registers/positions ...
- command-line editing and extensive completion
- IDE like build/review/edit features
- session state preservation
- configurable status line
- insert-mode completion
- multi-mode text folding
- extended scripting and expressions
- scripted plugins including remote file editing
- visual mode selection with char/line/block ranges
- comprehensive integrated help system with hypertext via ctags
- The ability to impress windows users with how l33t j00 4r3
- and many many more