Ranked in these QuestionsQuestion Ranking
Pro Amazing performance because of the Epiphany coprocessor
The Parallella Board makes use of the Epiphany III coprocessor which is invisible to the OS unless directly addressed through its APIs. It currently boasts 32 gigaflops from its 16-core variant with a promise of 100 gigaflops for a 64-core model which will be available in the future.
Pro Completely open source
Parallella uses open source hardware. The drivers are released as open source as well. All the details about the board designs and schematics can be found on GitHub.
Pro Great board for programmers to experiment on different platforms
The Parallella is a great board for programmers to experiment programmin on ARM, FPGA and the Epiphany architecture in one compact package.
Pro Ships with open source development tools geared towards Epiphany development
Parallella ships with several open source tools geared towards developing for the Epiphany architecture. Some of these tools include a C compiler, Eclipse, OpenCL SDK/compiler and runtime libraries.
Con Not great for media streaming
The Parallella board was built to give everyone access to a mini-supercomputer. It's strength lies in the Epiphany which makes it great for parallel computing and image processing, unfortunately it's not good with media (audio and video) streaming.
Con Existing software does not work out-of-the-box
Since it uses a different architecture than most boards, out-of-the-box software is not compatible with it. Instead, there's a huge GitHub repository with official ports of popular software compatible with the Parallella Board.