I worked for the company for 10 months during 2005.
The only good bit for me were the crew. Lovely bunch of people at LHR and the base isn't too big so you do get to know quite a few people.
I have to disagree with the point above about money. Yes you get London weighting, but I'm now with Virgin and am earning the same as a junior now as what I earned as lowest ranking crew at bmi. Everyone says us Virgin crew are poorly paid, but at bmi I was being paid pretty much the same for working probably 20+ hours a week more. Work that one out! If you want to do shorthaul scheduled then go and work for easyjet and at least get a bit more money!
You do get worked very very hard. Crewing rule the roost and do whatever they want with you, and your roster never stays as published. I felt like I had no life outside work for the 10 months I was there, and for my 5/6 days on did little but sleep and work. I usually got 3 or 4 nightstops per month, however they were usually only about 12 hours rest so you didn't usually get much more out of them than a quick drink at the hotel bar and then bed.
I left in Nov '05, so things might have changed since then but judging by the unhappy faces I see on the car park bus I can't imagine they have.
As someone else said, the company doesn't suit everyone, so I just thought I'd give my view as someone who it didn't work out for.