T-mobile is a great network if you're in the UK.

T-mobile, has excellent signal coverage, the tarfis offered by t-mobile are great, and very worthwhile having a look into before you go elsewhere.

The only faults I can find with t-mobile is if you roam in America, I can't comment for Europe as I haven't been there. But when you go to America, I feel that you are ripped off. I was charged 40p for a text message and only 25p for a picture message which is better value and you can add as much text as you please. The internet browsing was outrageously high at £7.50 a Megabyte. The only other fault I have noticed and aware of is slow delievery of telephone orders, I ordered my new phone a few months ago on the phone, it was a Sunday, and I was told the item wouldn't be delivered until the Friday, which is a long time considering I had paid £4.95 for it.

However, T-mobiles network makes up for this with the speed of the internet, it is very fast. T-mobiles customer service is great, anytime I have had a problem, which is rare I would phone up and i would be helped straight away and the problems would be solved then. Also, very fast.
Thanks for reading! I hope this has been of interest to you and has helped assist you in your decision.