I think that TabletDraw does not offer enough features to make it worth the money. I would consider waiting for the next generation or considering another program.
TabletDraw is an excellent product, which is very useful. I would personally wait until the next generation since it will likely get much better and the price will drop.
It depends on your reasons. If you need drawing program right now then go on and buy it, otherwise wait for a better and technologically advanced software.