Pros: Never replace batteries
Holds a long charge
Lights indicate when they're done charging
Cons: Nothing at all
If you have a Wii, you can't go without one of these. It's a wiimote charger, no more need for batteries.
I basically have this, but the brand I have is GigaWare (Wasn't on the site.). I believe this plugs into the wall, but mine plugs into my Wii via USB.
This product is absolutely amazing. You can just play Wii all day, then put the controllers in the charger when you go to bed. The next morning, they'll be fully charged.
I got one of these right when I got my Wii. I've never used batteries, and I don't get why people do.
When you get the product, you get special battery covers to put on your wiimotes. So put those on, then click the red Sync button on your Wii. Using a pen or something, push down the button on the cover of the wiimote so that it hits the red button inside (batteries are on the cover, so you cant just push the button inside the wiimote).
Overalll, if you have a Wii, get one of these!