Im a wacom user so im biased toward them and although i now have upgraded i used a Graphire for a year or so in uni and they were quite good.
...the 2c id put in as to what to choose is just make sure you get one that has interchangeable pen nibs...if he does get keen on using a tablet he'll wear em down pretty quick if he uses em a bit or has a heavy hand and it will get expensive if you keep needing to but new pens rather than just new nibs
"I like to have a thing suggested rather than told in full. When every detail is given, the mind rests satisfied, and the imagination loses the desire to use its own wings."
~Thomas Bailey Aldrich~