BMI Baby
You'll get lots of differing opinion here but beware of the source. There are an awful lot of BMI mainline pilots covering very long duty days for Baby at the moment, spending half their lives in taxis, working 12 hour days on a 45 minute report, without any crew food, and no sector pay. As mainline 737 pilots the union agreed to a temporary situation of us covering the shortfall of Baby crews in order to allow the airline to get on it's feet quickly. However, this has been going on for a long time now with no sign of it ending in the immediate future.
So on the one hand you may get some very negative feedback from mainline pilots 'on loan' to Baby (and rightly so...), but their situation is very different from Baby contracted crews. This also means that there is a definite shortfall of pilots within Baby. BMI's early attempts to encourage / bully 737 rated crews into Baby with the fear of redundancy at mainline hanging over their heads hasn't had the desired take-up, with the result that there are numerous revisions to the terms being offered to transferring mainline crew to make it more attractive. Also a recent spate of resignations from mainline has removed the pilot surplus, so once again it will soon become a seller's market! The result being that the terms offered to Baby new hire's might improve further.
As for the work pattern, probably typical low cost. Four sector days, short turnarounds, a mix of long and short sectors eg EMA-ALC-EMA-CDG-EMA. Eight days off a month, no pension, good productivity, bloody hard work, no crew meals (that should be sorted soon with a few more ASR's!) At least you'll build hours quickly if you need them.
Cheers