I've flown BMI for most of the past decade, only on trips between LHR and either the UK or the Republic of Ireland, usually on an A319. Service was fine for these short flights, although I initially was surprised that ordinary beverages (e.g. tea, coffee) were chargable.
I was disappointed when they went from a 2-cabin C/Y configuration to an all-Economy cabin, as they often moved me from my Y seat into a C seat for op-up reasons. Apparently they don't have lots of *G passengers and used *G as the basis for deciding to move me forward.
Their domestic lounge at LHR is quite nice and convenient for departures to either UK or Eire, although inbound to Europe
I usually pit-stop by the Star Gold lounge first to shower.
One of the nicest features of the BD *G lounge is that few noisy
Americans show up, so it is peaceful and quiet.