You can take a look at this review article: http://mummyfique.com/review-yoomi-feeding-system/ From what I've gathered (from other reviews as well), the product works. The tedious part is mostly the fact that the bottle had to be charged after every use. That being said, it is definitely convenient for night feeding (can easily get another family member to take over the bottle feeding) and for family outings (no need to bring along the bottle warmer etc).
I haven't but I've heard so many good things about it. It's really innovative and a seemingly perfect invention. Here's an image I found useful in case you don't really understand how the yoomi bottle works.