I suppose it depends on the bike path. If it takes twice as long for me to get to work on the bike path than it does on the road... I'm taking the road.
Or if it's a really crappy bike path, like potholes and such...
OR... if it's a "shared" bike path, like the one in Manly, where pedestrians are allowed on it as well... It seems that nobody pays attention to the center line or arrows on the path, walk in groups spread out over the whole path, or just walk out from behind a tree without checking if anybody is coming first... Screw that.
The Manly bike path ranges from being pointless slow (because of the reasons I mentioned before) to being just plain dangerous. AND this is while there's a pedestrian-only path right beside the bike path!
There's other paths that are awesome, and I use everyday to get to work... but some really suck.