I think the key to having a positive experience in joining BA is about managing expectations. I joined about 18 months ago and was overwhelmingly excited to finally be getting my 'dream job'. Has it proven to be so? Not always, no. But it's still a heck of a lot better than anywhere I've worked at in the past. The negatives are mainly a series of little niggling issues rather than anything big.
Negatives first; this is a big, soulless organisation. The people I work with are generally great (there is of course the odd exception, as with any company). However, chances are you won't fly with them again for a long time. Cabin crew change almost every sector, every two at best, so it's very hard to build any sort of camaraderie. On a multi sector day I find that can be particularly trying. I've done a few four sector days where I've had three different crews. You are very much just a number here. But the anonymity that brings can be a good thing!
'Cost cutting', 'tough trading environments', and the threat of Norwegian are constantly being rammed down our throats by management, all while the company is making £1bil+ profits. That starts to grate after a while. Pay is no longer industry leading, although it is still competitive in Europe. We are lagging behind what our American colleagues make in the US though
So far my experience of training has been a bit hit and miss. Our initial type rating was with CTC and we were constantly being told by our (mainly easyJet) trainers that the BA SOPs are hopeless. The result is that at times, even after 18 months I still feel like I'm often having to learn the BA way from the manuals, which are not particularly easy to navigate! The BA trainers are generally good, although there are one or two who are slightly harder work. Myself and the rest of my new joiner course all agree that in BA you often end up doubting your previous experience at other airlines, which can be rather disconcerting. I never used to be nervous going into the sim at my other airlines, but for some reason at BA I am. That being said, as an FO you are treated as more of a Captain in training and the gradient of command is much less apparent than at other airlines. I find I am constantly learning something new here.
The bidding process is overly complex, but this is due to change in 2018. At the moment the whole process takes about three weeks, and just when you think you've got what you wanted, you get roster assigned a trip over the only days you bid off. However, once final rosters are released your schedule is set in stone and the company don't touch it. If you get to learn Bidline Rules and how to swap properly, you actually end up with an awful lot of control over your life. I'm on the small Airbus and am yet to fly my original roster. I prefer day trips and swap for these with relative ease to the extent that I have only done 17 nights away from home in 2016. The only three day trips I've done have been standovers with a day off down route, and both of those have been out of choice when I've taken my wife or friends with me. I'm a season ticket holder at a very substandard football club and I've only missed one home game since I joined BA, and that was because I was skiing, not because of the company! There is no doubt that the schedules can be tiring, especially the increasingly common four sector day trips, but the control I have over my roster is excellent. The high level of work is also offset by very regular leave. With four weeks of leave and two additional duty free weeks I find I am never too far away from another extended stretch off. In fact, as I sit here writing this I'm on my 31st day of no flying in a row (One week of leave with wrap days, one duty free week, some fortuitous trading and now a very quiet reserve period).
BA don't offer a cosy or personal environment in which to work, but they offer stability, job security and reasonable pay. My pay is always on time. I can interact with the company as little or as much as I'd like. When I get home, they generally leave me alone. They were excellent and very accommodating earlier this year when I had to have an extended period off for surgery.
The thing that gets to me most at BA is the endless complexity of even the simplest tasks. Rules are chopped and changed and approvals are needed from several middle managers, often just to get something as simple as a new set of wings for your blazer. The corporate structure can be infuriating at times. This spills over into the flying which is EXTREMELY procedural when compared to other airlines. It feels like your freedom to actually fly the aircraft is somewhat restricted. However, in such a big organisation this standardisation is a necessary evil and you won't often fly with anyone that doesn't do it properly via the SOPs. That can be a positive at times, but I do miss hand flying a visual on a beautifully clear day.
BA is what you make of it. It's lonely, impersonal, at times infuriating, procedural and vast. It's also secure, varied, flexible, often very interesting and generally well paid (although Paypoint 34 isn't ideal).
At the end of the day, I see my family a lot more now than I ever used to, I enjoy good staff travel and fly with some great people to interesting places, staying in generally decent hotels. I'm content on short haul, but that's just my personality.
Join with your eyes wide open and I think you'll be fine.