bmi has a nice product, lovely fleet now at LHR (all new airbus fleet).
Downfalls are long days (4 sectors the norm), and high turnover of staff. Therefore, promotion at LHR is usually quite quick.
Pay isn't the best around, but the staff travel concessions are good. Not many exciting night-stops left either now.
Its a nice place to start, and a good brand you can be proud to work for (for a while anyway!).
TDB x