Hi there,
I am a long-term maintainer and for several years I was in the habit of going to WW every 12 mos or so to lose the 5-7 lbs that inevitably creep back on. It always worked GREAT, but all of a sudden when i went back in spring 2005 I found it wasn't working for me at all. I've been back once more since then and, again, found it just wasn't working.
When I looked back over old journals etc., I decided that for me the difference was when they changed the system so you get fewer daily points and a pool of 35 Flex points per week. At my weight (at the time) I was allowed 22 pts per day and I just COULD NOT stick to that little food. (Even with all the zero-point snacks in the world.) And though I rationally knew that this is what the Flex points were for, I couldn't shake the feeling that using them was "cheating." So I constantly felt either hungry or guilty.

My leader suggested just divvying up the 35 Flex points into 5/day and allotting myself 27 pts daily, but again, I just felt guilty, like I couldn't stick to the "real" plan. I got stuck in a cycle of losing .75-1 lb per week, then regaining it the next. Ultimately I figured maybe my head just wasn't in the right place for it and decided it wasn't worth the $$ I was paying so I gave it a break.
Fast-forward about two years and sure enough, the scale has gone up 15 lbs total (my greatest regain in 10+ years of maintaining). I am now in the process of losing those lbs but I am not doing it with WW -- I'm doing "my own" plan with support from 3FC. I'm allowing myself 1600 cals a day and journaling everything in FitDay... and it is working. I've lost 5 lbs in the first two weeks. (I also have never stopped exercising for more than a month or two in 10 yrs... so that certainly also contributes to re-losing as well as maintaining!)
Sorry to write such a long post, but just wanted to say, although WW is a proven plan, there are elements of it that just don't work for everyone. Personally I think it is just too darn restrictive for me and ends up being self-defeating.
Holly