I've been upgrading my MacBook Pro recently as it's getting on a bit (bought in Nov 2009). Had been a bit nervous about fiddling around with the hardware in it but upgraded the RAM recently and that was easy, so decided to have a go a the hard drive too. Again, really easy. This hard drive works absolutely perfectly, my MBP was already faster from the RAM upgrade but unexpectedly the hard drive upgrade made it run faster still. Applications like iPhoto now just pop up almost instantly and retrieve photos really quickly.
Now have loads of space and a faster laptop! Seems to slightly drain on the battery more than before as another poster mentioned, but similarly I've found that's true for doing stuff like sorting photos and web browsing but actually watching video seems to be the same if not slower. So a small trade up but totally one worth taking in my opinion.