So, today being Christmas and all, I got some great gifts. Now, somehow:^o, my dad knew that I liked fishing.

His gift was a portable Humminbird RF35 fish finder. It has a watch and a little green sonar bobber that you cast out on a spare pole. You can reel it in or let it sit, and the bobber transmits the sonar signals of the bottom back to the watch. Supposedly, it will show you the bottom, structure, fish and all the rest. Very nice thought put into the gift.
My question is:
Has anyone used this before, and if you have, how did it work? Is it one of those infomercial products like the infamous bazooka rod?
This is the most advanced finder-watch combo of the RF series, so if any in the series are quality then this is too.