It depends on what is important to you. the upgrade will give you a faster reboot time so if you battery comes out it will take about 5 minutes as opposed to closer to ten-fifteen. The OS is without a doubt slower to response when your searching form something. There are less bugs overall but a new setup takes time getting used to and of course like i said the slower response.
Don't touch it:Heavier (=slower)Additional steps are needed to get to the same places maneuvering through your bb...
You can have that with the opera browser.I only use it when the native browser doesn't work.