The Gliding discs are fabulous: easy to store, small enough to put in your suitcase when travelling (to do lunges in all directions, 'skater' moves, push-ups, etc. in a hotel room), affordable. Though if you have carpeting, you can do the same moves with paper plates (which is what Mindy did before she invented the Gliding discs) and if you have wood floors, you can use microfiber cleaning cloths or rags.
As for the Bean: I have it, but haven't used it much. It is good for the 'bean crunch' (actually, they showed a different way of doing this in their original commercials, which is more effective than the newer way they show: rock the Bean back while squeezing your lower abs in and raising your upper body), for back hyperextensions, and for stretching. It makes ab work more challenging than on the floor, but less so than on a stability ball (but there are some moves==like Superman's/supermen?--that you can do on the Bean and can't easily do on a stability ball).
My recommendation: the Gliding discs are affordable and effective, and if you'd rather use them then paper plates or rags, go for it.
The Bean has potential, but only if you have room for it and can easily access it, and want to add a bit of challenge to your ab/lower back work, but not as much as a stability ball.