I think a bit of perspective is needed here. There have been a lot of negative comments about BA - mostly I suspecy from people who have not worked for another airline.
What are the good bits - big airline with unparallelled opportunities (within the UK at least) to fly longhaul/shorthaul, Boeing/Airbus and if it is to your liking, management. Bidline at LHR once you move up the seniority list is great giving you some degree of control over your lifestyle. Being junior with Bidline is not quite so good as you tend to end up with blindlines (having your roster built from the leftover trips that nobody else wants). Carmen (a preferencing system) at Gatwick I would suggest is better for junior people as you get at least some of what you want. Roster stability is a huge plus - what is published on your roster is what you fly - unlike my previous company where what was published you could almost guarantee you would not fly. Pay, I guess is similar or slightly better than other UK airlines. Very easy to be a grey man/woman - turn up, fly the aeroplane, go home and never see management if you choose not to pay them a visit. Flying more hours than when I joined but still not working as hard as I used to in my previous existence. BA generally have an excellent reputation for a no blame safety culture. If you screw up BA are not interested in apportioning blame - they want to find out why and prevent it happening again. If you are prepared to take on the learning points that is generally the end of the matter - again unlike my previos employer where it seemed to be a case of sack the bloke and we'll investigate it afterwards.
Bad bits - big company where (at LHR anyway) it is hard to get to know people as the chances are you wont see them for a few years. Much better at LGW where the atmosphere is much more like other UK operators. Hopeless management structure where the faults of the company are easy to identify but no one can put right. Lots of militant unions. Working harder than we used to, but who isn't these days.
I love working for BA and if you want to fly out of the UK with one of the larger operators, I would wholeheartedly recommend it.