Go for it, but it's better if you know some of the KID and Nimzo lines first....
Grunfeld defense
The main problem with the grunfeld is the amount of theory needed before you can play it.
You need the normal exchange (a complete opening worth of theory by itself), the russian lines with Qb3, closed lines with Bf4, g3 setups with or without nf3 and early deviations with for example Na4 and Bd2. Every system has quite a bit of venom for black and have to be handled with care. Ofcourse once black does know what to do the opening is perfectly playable !
On the other side white only needs to know 1 system.

The main problem with the grunfeld is the amount of theory needed before you can play it.
You need the normal exchange (a complete opening worth of theory by itself), the russian lines with Qb3, closed lines with Bf4, g3 setups with or without nf3 and early deviations with for example Na4 and Bd2. Every system has quite a bit of venom for black and have to be handled with care. Ofcourse once black does know what to do the opening is perfectly playable !
On the other side white only needs to know 1 system.
And not to mention the 8.Rb1 lines, the 3.f3 lines, and thoses lines with an early h4...
people that say that you must know tons of theory are kidding themselves and others. It is 2014 any opening has tons of theory. The great thing about complex openings is that your opponent is not sure which complex line of theory you will enter, My best advice to learn theory is to play games outof that opening
While it is true that every opening has a certain amount of theory there are a few major differences with the grunfeld
1) The grunfeld leave the choice of sub variation almost completly to white. If you play for example the queensgambit declined white can basicly choose how to develop the darksquared bishop (g5, f4) and some independend setups like the exchange but the black side plays more or less the same once you know how to play these systems. In the grunfeld there are many ways white can develop and all these ways have poison (see point 2)
2) If you choose the wrong setup in the grunfeld you get a bad position almost by force. This goes about as far as switching 2 moves. For example i play the setup with Be3/Qd2 and Rc1 and depending on the way I develop you have to either play Nc6 first, or play Bg4 first. Developing the wrong piece first leads almost by force to a bad position where black will suffer (making the right choice leads to an equalish position)
Grunfeld is a perfectly fine opening but does requires (a lot) more time then the alternatives and a good memory because there are many concrete lines you have to know
I have thought about studying the Gruenfeld. It seems like a great opening. Your thoughts?? I am a class A player