Great responses so far. Although the new NJA contract changes things a little (mostly for the better, though a few things do amount to small concessions of sorts, well outweighed by the improvements in my view), there are some excellent older threads on the pros/cons of 121 vs fracs in general and 121 vs NJA in particular which you should definitely read. I am too lazy to post a link though.
I am one of the 121 guys (regionals, but including ACA/Indepedence where our contract was rather good as regionals go) who was initially sceptical about fractionals but now that I am here (NJA) would be as hard pressed to go back to the airline lifestyle as I would be to go from broadband back to dial-up.
If one is young enough to still have 25+ years at the airlines, the prospect of eventually enjoying a senior schedule at the majors and enjoying it for a good chunk of time, may be worth sticking it out at the "musical chairs" airline industry, if (big if to my mind) one can stomach the high probability of some bad luck along the way. I find the whole "stepping stone"/"get this job to get that job" mentality of the 121 airlines disheartening, along with the cr*p shoot of bunkruptcies, mergers, etc. and frequently having to go backwards to go forwards and all that. It gets old after a while. It seems like many of those I know from ACA who have not come to NJA, even after landing on their feet, are all mostly looking to jump ship a couple times more on the way to their dream job, and unless they are at Fedex, UPS or SWA (i.e. even if they are now at another major), they are constantly re-considering jumping ship.
Granted, there are no guarantees that some industry shakeup won't eventually hurt NJA, but it is a place where one can not only get an immediate, sharp improvement in QOL over most airline jobs (for years 1-2 at least), but also get benefits of long term growth and stability without nearly as much anxiety during the ride, as in the 121 world. And, except for a select few (Fedex, UPS esp.), the cargo world, while the clientelle (boxes) are less fickle than the internet-fares pax world, seem to schedule crews like dogmeat even compared to the regionals.
7n7 certainly isn't for everyone. But personally I agree with the previous poster's reasons for a 7 day NJ schedule wearing me out less than a 4 or 5 day regional schedule, and the days off are infinitely more enjoyable than the days off of an airline commuter. And there are alternatives to the 7n7 which at least pay even more as compensation.
NJA life isn 't perfect, and I agree it's generally inferior to a good senior, living-in-base airline schedule. But it seems to me that there is so much insecurity and roll of the dice in ever getting, much less maintaining, a senior live-in-domicile 121 lifestyle, that the gamble is only worth it for those who can factor in the likelihood of 2 or 3 job changes (startung at seniority zero again) and the possibility of never getting that golden goose lifestyle at all.
Maybe I'm all wrong, and the combo of massive age 60-65 retirements plus international, mostly trans-pacific asian growth will bring on another "catch me if you can" era of majors lifestyles, but that seems extremely unlikely compared to the frittering away effect of ever more LCCs on the golden goose dreams of life at the majors.