I did use the abroller years ago for about a month daily - and it was better than doing nothing, for sure, but somehow it rather trained my back muscles. Eventually I quit this equipment because I looked like a germophobic scrubbing the floor. Only recently I read a review about ab training exercises and equipment. The abroller scored worst. The only thing that helps me is running and skating.
I have tried both, and liked neither. The ab roller was uncomfortable on my back, and I didn't see any results at all. I used their video daily for about a month. The Gazelle was hard on my knees. The running motion while keeping your legs in the same position would really hurt in the back of my knees after about 20 minutes. I now have a treadmill and elliptical, and I like both.
I agree, the best thing is a treadmill and a elyptical machine. I get People magazine and I won't let myself read it unless I'm exercising on my treadmill. It has been a great motivator! I also TiVo some shows and watch them when I exercise.