4G likely to be throttled
Was with o2 for their coverage, but switched from o2 for the first time because my wife was on it. That was 18 months ago. Here is my experience.
Crap customer service, throttled speed to 0.30 Mbps on H/edge, constantly switching to 3g reducing my battery. not too bothered as I do not use a lot of web data but do pay £40+ a month. But was annoyed to find out that all new customer and existing customers where their contract term expires will be throttled regardless of package, ie unlimited data! Soon as my wifes contract came up for renewal, and without renewing her speed dropped from 7Mbps to 1Mbps. Tested over a three month period. Yes i am that anal specially when our household pays over £100 to T-mobile a month v VirginTV who get £40 and provide a more services that we actually use, including 50meg broadband and TIVO.
Post merger my phone was constantly switching between t-mobile and Orange. When on Orange no calls got through, text service was shite, texts were duplicated etc. On Orange I could only use 3g, no HSDPA - most sites and checking emails would result in a time-out/ retry. As soon as things were finalised between T&O I have been stuck on 3g and rarely have full bar. My guess is 4G is just a headline grabber. T-mobile has never been interested in data customers and likes to appeal to texters and facebookers. More than likely on 4G your max speed with unlimited internet packages will be 1Mbps as they will never fully invest in the infrastructure.
Plan on buying out the remainder of my contract this month as my wifes is renewing on the 19th. Probably moving back to o2 or Three. Been impressed with Three's website, customer service and more importantly their speeds on my mobile broadband for my laptop and tablet.