Seriously A lot of people do not seem to be giving it chance.
When I got it I managed up to about 800 too, and was finding it difficult to progress, so I left it, but after getting pro in all the other sports I went back to it and kept trying...
Eventually something clicked, I can't explain it but I understand how it works now, before I just flailed and got angry because some of my punches didn't even seem to count, but now I am a master.
In order of my preference;
Boxing>Tennis>Bowling>Golf>Baseball
Which is almost the order in which the complexity/depth of the motion sensing goes, because Boxing bowling and Tennis are in fact quite complex in what the Wii remote registers, everyone thinks tennis is just a timing thing to aim left and right, but it is much more. Golf is a little more simple, and baseball is very simple indeed.
My skill level in Boxing btw is now 2600+ It will take a while to get to 2700 though.
(Tennis I am about 2320, Golf about 1600, Bowling and baseball about 1200)
