Well I fancy making it my reply to 1.d4 and I have a book on it. Sometime in the next couple of days (when I can find a bit of time) I'll post a bit of info to share.
I get the impression it's quite "sharp" which I take to mean you can slip up and screw it up quite easily...
This is me screwing up the white side:
I didn't play it so much; but I think the main idea (especially for the main variation with e4 Nxc3 bxc3) is that White has a strong center he will be able to use on the long term if Black is not agressive enough; but Black develops quickly and is more comfortable in the beginning.
The main strategy for Black is therefore to put maximum pressure from the very beginning on the center and the h8a1 diagonal (with the a1 rook and c3 pawns, the main target being probably the d4 pawn).
rather than lines, you can try to remember typical moves. In the grunfeld, these are probably: c5 (you can "gambit" it, cause dxc5 completely destroys the oponent pawn structure) Qa5, Rfd8 or Rfe8, Nd7 also . Black can have his two rooks in the center pretty quickly I would say... On white side, early moves of the A rook should be expected
and don't exchange in the center if not necessary. you might feel it's more quiet, but so is it for your opponent.
and yes it's quite sharp for d4!
you may have look at these games. They are far from good (I like the endless end of the third though), but if you have questions about them, I will answer!
Anyway, I hope it helps!
Here I (Black) should have taken my advantage when I could take his bishop (his pieces are not very well coordinated yet, and he tries to be too offensive I would say). As I don't, he (same rating) is able to use his strong center to get a very clear advantage. I win at the very end by chance
Here you can see that though they are delayed, I play all the "typical moves"; and quickly have the two rooks playing. lower rated opponent, who brings out his queen one move too early (e3 would have been better for his plan).
Here my opponent (Black, higher rated) simplifies too quickly in the beginning; which gives me (White) a correct situation, despite a pretty bad opening.
I like the Grunfeld. Maybe I can help you understand it, chrspayn. Black needs to achieve explosive counterplay in the Grunfeld. Pressure against d4 is thematic. Black often obtains a queenside pawn majority while white gets a big center. Have you played any Grunfeld games on this site that you can point us to?
I don`t recommend the Gruenfeld as black if you are a player who thinks drawing a game of chess is worse than the plague.
However it works super duper great against some players so its good to have in the opening repertoire.
In practice the mix between boring and complex games is very noticable
and so controlling the game complexity is tough.Against weaker players they often don`t die a quick horrible death which is a bummer.
I like the Grunfeld but what bugs me is that it's not a complete solution. After 1. Nf3 Nf6 2. c4 g6 3. Nc3 d5, Black has an inferior version of the Grunfeld. If Black refrains from 3. ...d5, White can play e4, crushing hopes of a Grunfeld. Thus, unless you're fine with playing an inferior Grunfeld against the 1. Nf3 lines, you need one more opening. Unfortunately, I have yet to find something I really like.
BTW: The same thing happens if you play the Nimzo. 1. Nf3 Nf6 2. c4 e6 3. Nc3 Bb4 and there's no pin. However, unlike the Grunfeld line, this isn't clearly worse. Unless you play the Dutch or symmetrical lines against d4, life isn't so easy against 1. Nf3. It's the Achilles heel of my repertoire.