The M&M Rotor is worth the money, because it does its work nicely - for little money. This friendly little devil here provides satisfactory strong vibrations. The rotational speed can be variated in a not too wide, but also in a not too narrow range, so you might find the right speed for your needs. The low price of 200 Yen/ 1.95 US $ means, that you will not have a high-tec product in your hands, but the drawbacks are insignificant. This part is made from cheap plastic and I think, that the vibrating egg (~1" dia, ~2.25" length) will not be waterproof (don't drown it!), but that's okay. As well the battery compartment is a hassle to open, so be careful not to break its cover. The contact of the speed regulator is not the best, but the part works and the pot seems to be sturdy enough for a long life. Reading this, you might think: "Why should I buy this, then?" - well, I tell you: think of the price you'll pay for a toy, which will do a good job, concerning its ability to give orgasms. I absolutely recommend it for those, who don't have a vibro-egg and want to give such a try; it won't be a big loss for those, who will not like this variant of vibrators in the end. One big advantage (to me) is, that the speed is continuously variable, instead of having a number of vibrating programs you have to switch through (to come to a previous setting), which could be distracting and annoying.
All in all I only can recommend this little friend here for everybody - just give it a try!