Pros: Quiet, Fast, Can handle anything thrown at it
Cons: Sli issues, not greatly OCable
I've been using the Zotac GTX 590 GPU for the last few months and can not be happier. As of now, the GPU is the fastest dual chip card out there. I played pretty much every game you can think of including Crysis 2, Battlefield 3, Metro 2033 and I have yet to see the card underperforming. The 590 has 2 GPU cores that are found in the 580 series cards but these GPU cores on the 590 are downclocked and not as powerful as a 580. However when two of these cores gets together and become a single GPU, what you have is the fastest card in the market as of now. Even the GTX 680 performs 5-10% slower than a 590 if both GPUs are not Overclocked. Though it is not a secret that when 680 is OCed it can be 10% faster than an OCed 590 since the OCing headrom for 590 is not so high due to voltage limitations in the firmwares. There may rarely be micro stutering or SLI profile issues since the card itself is an SLI card, but these problems are usually solved via firmware updates.
If you are gaming in 1080p, you are pretty much set untill 2014 in the graphics department because this GPU will handle everything thrown at it. The only issue might be in 3Dvision. Although pretty much every single game out there can max in 3Dvision with a single 590, graphic intensive games such as Crysis 2 and Battlefield 3 need to be lowered in detail in order to maintein a steady 60 fps experience.
I am using a custom profile for the fan and the highest I have seen my custom profile fan speed was 75%, and I can easily say that the card runs very quiet even at 75%
590 has been a limited design and it is pretty hard to find it brand new anywhere because the production of the 590 has stopped few months ago, however since the release of Kepler, you can pretty much find these GPUs in 2nd hand with very attractive prices, and you would not regret it if you ever want to take advantage of one of these opportunitites. However be warned that if you ever want to have 2 590s aka a QUAD SLI setup, make sure that your PSU can support at least 1200 Watts.
I can not see myself upgrading again until another Dual GPU card comes along by Nvidia, either a 690 or a 790. The excitement that you will get via Dual GPU cards are incredible as they are engineering marvels.