My cross bike came with cantis and at first I thought that they were terrible. I had all sorts of trouble trying to adjust them- mostly trail and error in the beginning. I still wasn't satisfied with the results and almost decided to buy a set of V-brakes, but then I read/studied more about how the cantis work and finally got the hang of it. Here is a list of the things that have helped me the most:
1.) If your bike has those Z-link straddle wires, then throw those things in the trash because they are garbage. Replace them with this type of straddle wire:
2.) Once you have that then you can start setting them up correctly. Start by getting the toe of the pads set. I use a thick piece of plastic to put behind the end of the pad and tighten it up. It sets the toe perfectly- some people use a thick rubberband and/or other items to set the toe. They all work, just pick one.
3.) Make sure that the tension screw is as close to equal, on each brake arm, as possible. The easiest way to do this is to remove the straddle wire and use your hand to push the brake arm towards the rim.. Make note of how much pressure it takes to make the pad touch the rim- make sure that the other side requires the same amount of pressure and you are all set.
I've done the above and now my cross bike stops as good, if not slightly better, than my mountain bike that has V-brakes. The whole deal with cantilever brakes is to take the time to learn how to set them up- it probably won't all click the first or second time, but just keep at it and you will get everything figured out.