Lots of people seem to have had no patience with this game. However with a little bit of practice you can quickly work out how to throw the darts consistently. Persistence with the same grip is the key - I hold the controller with the buttons facing the right with my 4th finger on the A button and it works a treat. Have won 2 tournaments so far and am up to 6th in the world, however it took a while to figure it out. Have also had 2 9 darters.
My only gripes are that the opposition averages are far too good (although once you get the hang they need to be good to avoid a pasting), and the second one that nobody seems to have picked up on is the fact that there is a bug with the game durations in the tournaments. In the LV Desert Classic for example, all rounds were best of 11 legs (first to 6) instead of becoming longer as the tournament progresses. Thats why I have done so well - I think I might struggle in a really long match but havent had the chance.
That aside (and I believe a fix is on the way for this) it's great fun and really addictive, but do be patient because you wont master it within the first few hours - it will take a few days