UPDATE: A small patch came in today, and the motion controls seem somewhat better, and difficulty appears somewhat tweaked.. esp. in boxing. There may be other fixes, but I'll up from 2-3 stars.
It seems that much like with the Wii launch some developers have made some inferior games to cash in. I would place Motionsports in this category.
There are some fun games in here so it's not a complete disaster.
On the good side -
are all decent although football and equestrian are almost "turn based" (seems as this was a design decision not a function of the hardware) as you must perform your move well before the motion actually happens which is odd since Skiing and hanggliding are both extremely responsive.
On the diaster/broken mechanics side I would place Boxing and Soccer. Boxing difficulty seems ridiculous. You can connect with many punches on just the second boxer after the "tutorial" boxer and if he hits you a couple of times you're going down. In soccer the setup for kicking the ball pretty much breaks the gameplay as it is extremely difficult to tell where exactly on your floor you need to kick. It does say "shoot" but only for a very brief moment.
There is also no online multiplayer (I believe there is in Microsoft sports) so the game gets a negative there.
Also, there is no broader game.. would be nice if they could have included some sort of party game setup so the minigames don't feel so detached.