Are they worth buying?

Just want something to read off and clear any fault codes stored in my ECU.

http://cgi.ebay.co.uk/U380-OBD-2-II-...1%7C240%3A1318


I'm looking at something like this. Do they do exactly what it says on the tin, or will I need something a bit better? It will only be used once in a blue moon, so I don't expect to save the world with it or anything


Cheers
Rich