I started on a hybrid, tried a road bike, (a second-hand Trek 1000), loved it, and have never looked back.
It took me a couple of weeks of daily riding for my upper back and neck muscles to become accustomed to the position.
Ultimately, it depends on why you ride and what riding does for you. I love my road bikes because with the barest of efforts--the lightest pedal stroke, or a mere wiggle of the fingers--THINGS HAPPEN. The speed, lightness of handling, and the ease with which it goes, steers and stops were instantly addictive. It was literally the very first pedal stroke on the road bike that sucked me right in.
By comparison, the hybrid felt like I was dragging around an anvil behind the bike. It was a great workout, don't get me wrong, but I ride for more than just working-out. Even so, I put 3,800 miles on the thing in a year, riding everywhere including rides people said shouldn't (and even couldn't) be done with a hybrid.
I'm on my second road bike already, yet I've still logged more miles on the hybrid. But since April barely a couple of hundred.
Edit: Oh, and the shifters. That took even less time to adjust to than the position.
Last edited by tsl; 12-10-07 at 07:13 PM.