Hi, i'm new to the BB world.

I was wondering what advantages there are to upgrading the OS on an 8110? Am i going to gain any functionality or noticeable performance? Any disadvantages?
thx.

Depends on what version you are on now. If you move to the 4.5 series OS, you'll gain HTML email, support for larger media cards, and plenty of other improvements.

I would say you gain an overall performance improvement on the device and some extras on the apps and hardware support