Well its the way you look at it MH. It is a known fact that t-mobile has the worst coverage outside the major towns and with the network assets of Orange and t-mobile merging, t-mobile customers can expect better coverage. So if you are happen to be on a good deal with t-mobile, it should actually be good. My company's official phones are on t-mobile and we get pathetic in-building coverage.
I am not sure about this Nik. The figures for T-Mobile and Orange are not that dissimilar. Right now, T-Mobile has around 10,000 2G base stations, while Orange runs about 13,000; both companies operate around 7,000 3G base stations.
Now, superficially, you can say that 10,000 + 13,000 will be a lot more, but alas that is not the case. Unfortunately their plans are to dismantle masts, and to reduce the dual coverage in areas served by both. This is part of the rationale, the 'synergy' cost saving motivation, for the deal in the first place.
The biggest savings will come from dismantling redundant network infrastructure, as Orange and T-Mobile have heavily overlapping networks.
In any case, there is a well known difficulty with the 1800 MHz signals used by both networks: they simply do not penetrate buildings in the way that the 900 MHz signal used by O2 and Vodafone do. You may find an improvement if the T-Mobile is particularly weak in your area, but don't count on it I should say.
