Hi mark,
I worked for bmibaby in 2007 as a CSA at EMA, and unless the interview format has changed, you're sent off to a room to do some basic geography, maths and bmibaby information tests, and then after they're marked, you go for a 2-on-1 interview with some of the ground services team. I found out within about 2 weeks whether I had the job.
Moneywise they're probably better than most handling agents, as the job does offer lots of overtime and you're paid commission on various targets such as excess baggage and sales. All contracts were subject to a probationary period, probably now they've rephrased this to temporary contract, and within six months 8 of the 11 people on my course had left. Staff travel after six months on bmi services (no Star Alliance) and a number of incentives to work to.
The base has some fantastic staff, many I've stayed in touch with after leaving. The duty managers do a great job of keeping the staff smiling under very difficult conditions (clapped out aircraft, constant delays, fed up customers) and as a team, at least when I was there, everyone more or less got on very well. Sadly, my enthusiasm doesn't stretch much beyond that, and the job was thankless, upper managers were difficult, unhelpful and unapproachable and all of us who've left and are still in touch seem to share the idea that it was good money, a good team, but just appaling organisation and not the nicest of corporate cultures, though from what I've learnt about mainline, this seems to be a bmi thing in general. bmi must however look good on your CV, and is a great taste of the airline industry, because I quickly moved to another (charter) airline as crew, and am absolutely loving it; good money, nice crew and decent management thrown in.
bmibaby as a company is facing a change of ownership, and lots of competition from larger and better-managed low-cost airlines. Nobody yet knows how the airline is going to be carved up. You have to decide for yourself, I guess, but at the moment if you have a stable permanent job, it might be an idea to stick to it.