The only interesting things from previews:
From tomshardware:
1-Pay the same $1,000 for a GeForce GTX 690 if you only want one dual-slot card and your case accommodates the long board. It remains the fastest graphics solution we’ve ever tested, so there's no real reason not to favor it over Titan.
2-The Titan isn’t worth $600 more than a Radeon HD 7970 GHz Edition. Two of AMD’s cards are going to be faster and cost less. Of course, they’re also distractingly loud when you hit them with a demanding load. Make sure you have room for two dual-slot cards with one vacant space between them. Typically, I frown on such inelegance, but more speed for $200 less could be worth the trade-off in a roomy case.
3-Some BS
4-Buy a GeForce GTX Titan if you have a trio of 1920x1080/2560x1440/2560x1600 screens and fully intend to use two or three cards in SLI. In the most demanding titles, two GK110s scale much more linearly than four GK104s (dual GeForce GTX 690s). Three Titan cards are just Ludicrous Gibs!
From guru3d