Pros: These are incredibly fast. I use 2 of them in a Supermicro X9DAE board with 256GB of ram. I get a cinebench score of 26.10. These processors will handle anything that you throw at them. I use dual Corsair H80i's for cooling.
Cons: Price. Really, almost 2 grand? I suppose with no competition at the top, Intel can charge whatever they want.
Pros: I own one! (Its still boxed, waiting for the machine to drop it into). I'm excited to see what this thing can do (Will be used in an HP Z420 Workstation as an ESX5.1 host.)
Cons: To the average Proc buyer, this would be a very, very expensive purchase, that they probably wouldn't be able to utilize fully. But I'm going to tax it heavily, and I SAVED money buying this on new egg vs during the HP build.......so not a Con for me.
Pros: 16 physical cores (2-Socket WS Mobo) and 128GB of RAM take your productivity to entirely new levels. If your workstation is a *tool* and not a toy, these 8-core E5 CPUs decimate even the vaunted 3960X 6-core units by an order of magnitude in C4D and AE/Premiere. If you're a video and/or 3D motion graphics pro, just get two of these via any means possible -- sell blood, superfluous appendages, excess children, or whatever you need to do to get these. You'll make enough...
Cons: 150 watts is a LOT of energy for thermal regulation, exacerbated when you have TWO of these monsters. Your entire build needs to revolve around sufficient cooling, as 300 watts of heat will turn the inside of your case into an "Easy Bake" oven without sufficient airflow. This is the first CPU that I felt really demanded the use of liquid cooling, which I have avoided until now. Obviously, a 1000+ watt PSU is also necessary now when you begin to cram GPU's, RAM, and 15...
Pros: Tears through multithreaded apps. Fantastic for doing graphics software development with lots of multithreaded code. Makes it easy to see when your code is able to saturate the CPU and scale well with respect to core count. Further performance work can then target reducing overhead (minimizing locks and synchronizaton), and increasing throughput (optimizing inner-loops, and special-casing high-impact combinations of general rendering kernels).
Cons: Expensive. Runs hot. Multipliers are locked hard, so no overclocking.