Is it better to leave 3G data turned off?

I have iPhone 4S and I was curious weather or not I should turn off my data at all or just keep it on. I don't know the difference or what it will effect if I turn it off.

Well one time I went on holiday so I had to turn my 3G data off and when I came back I forgot to turn it back on. Believe me everything loaded so slow, so I kept reporting my router thinking it was my rubbish network but then I remembered my 3G Data. So I turned it back on and my phone was back to normal! Lmao

Well first off if you don't have 3G included in your plan don't use it at all but I have 500mb of data and just keep mine off all the time unless I go out where there's no Wi-Fi, just always turn it off and use Wi-Fi if you have Wi-Fi if not use 3G but don't watch YouTube videos with 3G because it uses way to much data. If you are on Bell get an app called Self Serve it monitors your data usage if not look up Data usage monitoring apps for whatever company you are with.

Hope this helps.

Yes.

1) Just because you aren't searching the Internet, doesn't mean the phone isn't using data in the background (e.g.checking for notifications, new emails, your location, updates). If you don't have a data allocation, this can be expensive.
2) Improved battery life

Hope this helps!