My QOL has been very good, but I'm probably more the exception than the rule. For the year 2012 the longest I've been gone from home was 13 days. The only month this year in which I wasn't awarded a split line (ie aprox. 9 on/6 off) and was available for the full 18 days, I had a 4 day long call reserve stint in ATL wherein I was able to jumpseat home. In the US you'll spend more time in ATL than anywhere else, so for me living in an adjacent state I'll usually jumpseat home knowing that I can easily make that 12 hour call out back to ATL if need be. For QOL, this has been paramount, and I even save the company money on hotels.
So for me, living in the southeast and having an extremely understanding gf has made life pretty damn good. To illustrate the other side of things, I had lunch the other day with another FO friend of equal seniority whom had just finished a 40 day trip. He was scheduled the 18 days straight with the last day ending on the 26th of the month. He was then available for the first 18 days of the next month. After completing the first 18 days scheduling decided to extend him the last 4 days of the month, thus rolling him into the next 18 for a total of 40 days straight. This is all legal, as 4 days is the max one can be extended. These are the horror stories/circumstances that one needs to fully appreciate before considering this.
In fairness to Omni, and in parroting previous posters, there's far from a rose-tinted analysis presented at the interview. They paint a very accurate picture and almost try to convince you out of it.
For point of reference, I'm in my mid 20's and don't necessarily intend to make a career of this; my summation is this: Omni is by far the most rewarding, challenging, heartbreaking, exhausting, interesting flying you will ever do. The camaraderie is probably unmatched. Someday, when/if you move on to that legacy job, you'll know that the pinnacle of your aviation career is already behind you, and in a way, you're on the downhill.