I purchased rechargeable batteries from Groupon (product name starts with a W) and despite charging them, the product would not work. Yet these same batteries work on remotes, etc.
I, fortunately, had a different brand of batteries which I tried and the product works like a charm.
The 30 speeds provide different sensations so you'll have a great time figuring out what works for you. Make sure your batteries are fully charged as the speeds will not function as well as they should with batteries that are dying.
Like one or two other people, since I'm small, I had concerns about the top part/head being uncomfortable going in, but you just need to use lube ; )
I'm very pleased with my purchase and would repurchase again if this one gave out.