Personally I mainly want it for PhotoShop work and other 2D graphics editing/creation, all reports I've heard have stated that Matrox's 'GigaColor' has an immediately evident impact.
Icrontic had a nice write-up on the impact of it.
That paired with Matrox's typically stellar 2D image quality make for a very pleasant time.
I'll be interested to see how much GigaColor impacts DVD's, and older games that don't need more then 2bits of alpha.
And finally I can get Matrox 2D, along with solid 3D.
It has the best 3D feature set available, along with en excellent FSAA implementation that looks to provide a minimal performance hit while retaining fantastic visual quality.
Granted, it doesnt hold up to the R8500/GF4 Ti42000 regularly, but it gets close when FSAA is applied.
Of course I could always take a stab at 1600x1200 + FSAA, at that point it seems to over-take the GF4 Ti4600, but I find 1024x768 preferable for 3D.
Still, as much as I'd love to have Matrox calibar 2D and decent gaming, and GigaColor looks to be an extremely pleasant feature... I just can't justify $400.
I wish they would pull out a 64MB board for $300... at that price I'd proably go for it.