Does any one use those? How good are they, like in terms of pressure sesitivity translating into different line thicknesses.
Can you sketch really fast, and it'll show the result on screen, instantly.
I am planning to get one, but havn't really found much info on the web.
Any help will be greatly appreaciated.

Any body.....need advice fast

I've used a couple of low end models, one was a Jam Pad I believe, and I forget the other. the Jam Pad was ok. I'd expect higher end models to be much better though because the Jam Pad had decent response and sensitivity. If you are just tinkering around or wanting something so you can easily draw directly to an application, or something like that, it would be more than sufficient. If you are doing something more complex or indepth, you might need to look to a higher end product.

A few Google search results:

http://www.tweakers.com.au/articles/misc/graphire2/page1.asp
http://arttech.about.com/library/ec/reviews/aafpr_wacom_graphire.htm
http://www.wordboost.com/a/Wacom_Intuos2_9x12_Graphics_Tablet_USB_B000060PEW.html

Do a search on google for the keywords: graphics tablet review
and you'll get a decent amount of results.

Thanks a ton friends.
Will keep you guys informed about the one that I buy.
Akshay