A lot of changes for this new version:
[*] New layout, much better than the previous one
[*] New rom-recognition system (recognizes more files, and much faster)
[*] Fixed most bugs from version 2.1
[*] Added support for downloading Trainers & Pogoshell Themes
Also a lot of new functions
[*] "Favorites": add your games in the favorites menu. You can assign a bitmap to each favorite.
[*] 2 display modes: a short one (the windows looks small and smart) and the normal one
[*] Tray icon mode - to send GBArms in the tray
[*] Autocheck function: to check for new roms automatically
There is actually a lot more changes. Read the whole changelog here.
See screenshots here: [1] [2] [3] [4] [5]
Download GBArms 2.2 Beta Rar File (~630kb) or Zip File (~635kb)
Also try the Resource Downloader, to download plenty of pictures/nfos at the same time, here.