I find it very accurate on all the games I have. Wii Play and RE4 in particular are very accurate.
Go into the Wii system settings if you are experiencing trouble and adjust the sensor bar calibration. Depending on how close/far you are from the screen affects your ability to aim accurately. Adjust/calibrate from here and test, it should work great.
Should also help a bit if for example your TV is positioned particularly higher or lower than normal. But best bet is to position TV in a more user friendly location.
Also make sure your batteries are not on their way out as this can cause problems.







