I'm tainted, as Mithro offered me a board to "have a play with, no strings attached", and I've been hacking away on it for a while. Apparently it is the 3rd board ever made . So here's my biased review.
Value for moneyPricing is really good, esp given that it doesn't have any of the discounts that 'official' dev board manufactures get. It must be priced pretty close to cost. You can pay $800 for the same FPGA on a module (eg
https://www.opalkelly.com/products/xem6310mt/)
Video InterfacesMost video oriented FPGA devboards have only one or two of each connector - e.g. the US$500 Digilent Nexys Video (HDMI-in, HDMI-out, MiniDisplayPort) or US$75 Scarab miniSpartan6+ (HDMI in, HDMI out, with only 1/5th the FPGA logic), and they also have a lot of cruft that you don't really need for pure digital video work - switches. LEDs, small expansion ports. This is the only board I've seen that has two HDMI inputs and two HDMI outputs, and DisplayPort in and out.
For all the Spartan-6 based boards HDMI tops out a little over 720p due to the clocking limits of 1,050Mb/s on standard I/O pins, and even for the newer Artix-7 boards 1080p is a little out of the FPGA's spec (but it does work). As the DisplayPort is on the high speed transceivers, it can move 2.7Gb/s per channel. and as it has all four channels it can REALLY can do 4k resolutions (either 2160p60 in YCC 422 or 2160p30 in RGB/YCC 422).
Other interfacesAs mentioned it is light on more generic I/O and expansion, but then it is a purpose-designed board.
MemoryI haven't looked into it, but Video memory bandwidth is always going to be a problem. If you are doing UHD video you won't be able to squirt 10Gb/s of video into RAM and suck it back out again. 2.4GB/s of sustained bandwidth is too much to ask for. The board has got DDR-1600 on it, so it should be fine for processing 1080p, streams, but not 2160p. So it's not a platform for 4K development unless the video stream stays within the FPGA.
It is plenty of memory if you want to run an embedded soft-CPU design acting as command and control of the video streams.
FPGA type and sizeIt is quite rare for a Spartan 6 devboard to have the 'T' model (the ones with high-speed transceivers) on it. I found the transceivers to be a real pain to get to grips with - lots of exceptions and oddness to deal with, especially with the clocking options. I've got them working but I'm still getting to grips with them after two weeks. Everything seems to be planed out correctly (e.g. reference clocks on the correct pins), with just a few gotchas on the prototype boards - but that is what prototypes are for!
The FPGA size is my main concern - video processing uses lots of logic - relatively fast wide buses (e.g. using internal RGB 12:12:12 video data paths at 150MHz), and 58 DSP blocks. A matrix operation (e..g colour space conversion) might require 9 DSP blocks, so by the time you allow mixed RGB/YCC inputs over half your DSP blocks have been used.
However, this system is designed for when you have full control over the input and output formats (e.g using EDID to advertise only RGB support), so it is the right-sized FPGA for the system's target use.
Debug issuesDebug - Without some generic pins to hook up to my logic analyser, debug is a bit more painful than I would like. I'm currently using a passive microSD->JTAG adapter to extract a couple of bits of debug. If somebody could implement a multi-channel logic analyser with output to a HDMI screen that would be really cool. There is the option to get data off the board over the gigabit ethernet too, but I don't have any experience of that.
Who is this for?It isn't for the first time FPGA user, you don't have much fun things to experiment with. Maybe look at the miniSpartan6+ or a Digilent board.
If you are looking for an FPGA board to play with switching and mixing and light processing of digital video signals (e.g. brightness, colour processing, audio processing) it is going to be perfect.
If you want to play with or prototype DisplayPort it is going to be perfect too - it costs maybe half as much as an DisplayPort FMC card.
If you want to perform simple processing of video from two cameras (e.g. machine vision) it might be a good fit, but you may have problems with offloading the processed data to your host.
If you want to do extensive video processing you most likely will find the FPGA too small, but you will be spending a lot more for a less 'open' board.