I had many issues with my '00 Golf's hood latch and release. I would have to "pump" the release to get it to pop, when it didn't, I resorted to pulling farther on the release handle... until I broke the bracket underneath. Even when it did pop, it wouldn't jump enough, so I had to have someone pull up on it as I pulled the handle (or wedge something between the hood and the grill). After the handle broke, I used a pliers until the ball was down to a couple threads. When there were just a few threads left, I replaced the entire cable and release handle, only to resume needing extra help 50% of the time. It would work slightly better after an application of PB Blaster to the latch mechanism.
Things I learned in the process:
The release handle bracket is terribly designed, requiring the sliding of the bare cable along some soft plastic. It will eventually wear out (meaning you'll have to pull the release lever farther to get the latch to release). The dealer that sold me the bracket said they replace them all the time.
The rubber bumpers the hood rests on can be raised and lowered by screwing them in (by hand), which may alleviate some of the issue, allowing the hood to fall a bit farther.
And a little searching finds this old thread:
http://forums.tdiclub.com/showthread.php?t=53713 that indicates a problem with spring tension could be to blame too.