The iTerm2 features page[1] has a pretty good run-down of all the extra stuff it can do. Personally, I'm a big fan of the split panes, and I use iTerm2 full screen with two panes.

That said, almost identical behaviour can be had in fullscreen with two Terminal windows sharing a full screen desktop space.

I also enjoy having my terminal be a slightly-transparent black rectangular slate, with no title bars, corner curving, etc., but that's purely preference and has no impact on functionality.

[1] https://www.iterm2.com/features.html