I've never tried the ab lounger..but I did have an ab roller that you put on the ground and used ...and it worked really well!!
Now though I just do crunches every night to maintain a flat stomach. I think that I've gotten the same effect from those.
But sometimes its just fun to use machinery! haha...
If I understand what you are calling the Ab Lounger, then I've tried it, but only twice. At a friends house, and at my parents house... It does work your muscles... and I'm sure if you got on and was consistant on it then it would help.