Yeah, it looks like it could be fun, but you are mainly working your forearms while holding on...your swinging too much to get your abs, and you're not really pulling/pushing at all, just adjusting your hands in...so your upper body isn't getting too much of a workout.
Try this: L-Pullup, lower, then from L-position raise your legs up to the other bar. Switch your hands to the horizontal bars, lower your legs in control, bending only at the hips, to a dead hang, then jump both hands to the outer bar at the same time, utilizing a powerful kip of your hips and back to propel yourself up and out. Pull legs back into L-Position and repeat.
THAT will be a good upper body workout.