Overall the GeForce 9800 GX2 works really well. Installation is just as easy as with any other graphics card. Insert the card into the PCI-Express slot, get the power cables connected and ready you are. After driver installation there is no need to mess around with SLI settings, the two cards are immediately enabled to render hand in hand.
NVIDIA makes it very clear that this is a premium performance product not for everybody. If you play in resolutions below 1600x1200 there is little gain by using two GPUs, especially when you don't have a really fast CPU. When you crank up the resolution and AA settings however, the SLI performance effect becomes apparent. In many benchmarks we saw close to 100% scaling. The GeForce 9800 GX2's natural habitat is a high-end system with big 2560x1600 screen connected. Here you could use very high AA settings in most games and still have a great playing experience.
But the price ... a $599 videocard is so 2006. Back then people were ready to pay insane prices for their graphics card. Nowadays most action happens below 300 bucks. Of course you can argue that you get two cards for $600, which is twice $300. But considering recent prices for the GeForce 8800 GT or the 9600 GT, which are both sub-$200 you could buy two of these cards plus an SLI motherboard for the GX2 price. On the other hand the GX2 will work in any motherboard with any chipset, not only NVIDIA chipsets, which will be useful when you just bought this brand-new X48 motherboard.
The new cooling concept of NVIDIA works extremely well. Placement of the cooler and fan in the middle has so many advantages, I wonder why nobody came up with this earlier. The Zotac GeForce 9800 GX2 runs cool and quiet which is something you wouldn't expect from a dual-GPU card.
Having an HDMI port on this card is definitely nice. Even though the card is way too powerful for just video playback, it will be loads of fun playing games on a 60" screen in full HD and beyond. Overall the GeForce 9800 GX2 is a solid product, but certainly not for everyone.