I used it today and yesterday and stayed at the premier inn right next door. I'm sure Brum city centre will be great once they've finished digging it up, whenever that might be. The station seemed to be less annoying than in the past, maybe it was my timings, but it felt less congested.
Worst thing to me about Brum city centre (and I don't have that much experience) is the public realm/access between the city centre and the ICC/Library area, with the massive ring road separating the two. Currently the best route is through that crappy shopping centre, which gets shut at night, causing much confusion to non-brummies like me and the 50 Irishmen following me last night.