It seems everyone hates these bags except me. I've been using the Airjet bags (55, 45 and 25l) as my main bags for - well I'm not sure but it's 5 or 6 years I'd say. They're all still going strong, in good nick after plenty of use, including bashing through undergrowth and being thrown across streams and generally chucked about. Not abuse, just shall we say "robust" use. They have a few cracks on the waterproof backing, but that's not really a major issue - I use a waterproof inner anyway. I find them comfortable when packed properly.
Anyway, that's my experience, everybody else hates them. They're probably right.