I have been working my way around Obj-C for the past two weeks.
It's recommended to learn Obj-C to program mac applications (at least to program the user interface) and I have to say that so far I like it. Basically Obj-C gives regular C Object Oriented Programming (OOP) capabilities. I'm more used to the Java way of doing things, but they are not that different.
One of my motivations lately has been the mac research website, I would recommended to any scientist considering transitioning from windows to mac as their research platform. My favorite part of this website so far is the Obj-C/Cocoa tutorials for scientists, and it's the way I have been learning Obj-C. I hope you will enjoy it.