I'm interested in these toys too.
You may want to check these discussions:
Electro Sex and Toys
E-stim, Opinons/Thoughts? Is it painful?

I quite like them i have the power box attachment for this 1
link

Out of my collection of stuff (and i have quite a bit now ) this is my favourite and can have a good time with it even when your on your own.

For someone new to it maybe the rubber or the leather 1s would be more comfortable until you can figure whether its for you or not its a lot cheaper that way

They are great as long as you know what you are doing. I have over twenty attachments(some are homemade) and three different power boxes. Are you male or female? They can be painful, but not damaging, if you are not careful. The sensation is not necessarily the same as sex, but they are able to induce ejaculation.
I have actually found that the ones that I have made myself are better, since I designed them for personal use.

This is the first time I have ever been on a forum, so do not know what to expect.