There isn't one airline in the world that is perfect or has absolutely ideal conditions for cabin crew, and a lot of members of this website choose to attack the down sides of a particular airline, and in some cases make them a lot worse than they seem. It's an excellent community to vent & to learn a bit about the industry, but everything has to be taken with a pinch of salt.
bmi has it's difficulties, and at the moment is going through a bit of a rough patch in testing out new ideas & product "enhancements" which isn't going down too well with the crews. Now it seems the company is like working for any other no-frills outfit, however you can progress onto more senior positions or longhaul fairly quickly if all is to be believed that mainline has an extremely high turn over of staff.
I can't speak for conditions as I don't work for bmi but bmibaby, but I can tell you it's definately worth giving it a shot. If you don't like it after a year, having a respected carrier like bmi (and your flag carrier LOT) on a resumé will look pretty good if you wanted to go for BA again. Who knows? You might even like it over here!