Having flown in and out of BHX/LHR T4/MANT2 in the past year BHX was easily the best passenger experience. The departure central security search at BHX was particularly easy to navigate compared to MAN T2 which was very slow and disorganised. The kids Skyzone at BHX also helped keep my son entertained which helped kill some time.
That said, agree that the check-in area at BHX is cramped at peak times whilst the size of the immigration hall / baggage delivery could be improved. The E gate system never works for me in arrivals first time - but that could be me. Personally I don't like having to walking through duty free but this seems to be the trend now and I suppose it make sense in terms of revenue generation.