Got to add a different spin on this...
I joined CX with a little bit of experience in my early 20's. I enjoyed HK for a few years before the inevitability of living in HK and working for CX with a young family kicked in and I couldn't wait to get out. By that point I had upgraded and had 1000+ hours in a window seat (one of the few benefits of a 330 upgrade, you get enough practice to get quite good quite quickly) which basically meant I had a choice of decent gigs back home. I am now coming up to a LHS in a big(ish) jet and living at home. Money is decent, life is good.
The reality is that CX is now a modern apprenticeship; the days of GA etc being a pathway to the top jobs are largely a thing of the past in my opinion. The industry has changed. Not sure how the 2 SO thing has changed the timescales of all of this but it certainly worked for me.
That said, they really are complete pricks to work for. Believe every word of it. Expect them to bully, lie and manipulate at every opportunity. Just make sure you use the anonymity of being a number in a massive company to restore some balance. I certainly did and don't regret it for a second.
If you're young, free and single and in your early 20's I still think it is one of, if not THE best way to get started in the industry. You may not end up better pilot than the ex GA guy but where else can you spend a week every month (or live) surfing and sh*gging in Bali, Phuket etc if you choose to? (FYI I did my stint in GA, very useful but not necessary in a modern jet IMO). Especially if you end up on the 777, lifestyle is great. Just be under no illusions, it is absolutely NOT a career and won't ever be again. Which is quite sad in truth but c'est la vie...
Joining and then leaving CX were the best things I ever did.