I've moved to 3 from O2 last month. I decided on the Rolling 30 day £15 a month sim, it's a good deal.
My main reasons for switching to 3:
- 1GB data (Most carriers are only offering 500mb on a rolling contract)
- Faster 3G speeds
- Free Tethering
The signal coverage in my home area is not great with 3. I get one bar 3G which disappears when I touch the iPhone 4's weak spot, I've had two dropped calls from this (but that's another story). It will reconnect to Oranges GPRS/E network but it's not instant.
I wasn't too happy with 3 Carrier profile switching off the option to turn 3G off, but you can choose GPRS/Edge only in settings>carrier and choosing 3 NOT 3(3G), unsure if this will help with battery because as far I can tell the 3G radio is still on.
I was also very unhappy with the content filter. It seems so ridiculous. However after some searching around I found this:
http://www.3g.co.uk/3GForum/showpost.php?p=451521&postcount=129
This is basically saying you can get around the filter by switching your Internet add on from internet Max to X-series Silver. They both cost the same with the same 1GB data allowance but the X-series does not have the filter (or has a less obtrusive filter). I left a message on 3 blogs page (
http://blog.three.co.uk/ - The mods are very active here and will contact you with any problems you have) asking if this is widely practised by 3. I received an email response the next day asking what number and at what time is best to contact me. 3 phoned me up later that day asking how they can help. The CS operator was very helpful, she cancelled my previous add on (internet max) and added the X-series silver.
Since then I have not seen the Content filter page. Say what you will about 3's CS but i've had absolutely not problems with them, they've solved all of my problems.
Next is Speed. I've had mixed results with 3's speeds. The fastest i've got from them so far is 1.98 mb Down and 1.48 MB Up. To me this is amazing and sometimes Surpasses my home internet Speeds (I live in a rural area and quite far from my exchange). I have noticed considerable slow down in the evening whilst at work (where I get constant 4 bar signal - Dropping to 2 with the weak spot) Sometimes I'll get Time out errors, I'm assuming this is due to network overload as a lot of people use 3 as their broadband provider near my Work. 3 are supposedly upgrading all their equipment to handle these peak times, but time will tell if this is true.
Overall I'm very happy with my transition to 3. But they do need to sort out the network switching from 3G to Edge/GPRS to avoid dropped calls and to upgrade their equipment to avoid slow down and overloading at peak times.
Hope this help you in your decision!