[vidarh]

Vs Xeon Phi: Cost, complexity, power. Look at pictures of the Xeon Phi cards. They're covered in heat sink, and with a fan. For comparison, the Epiphany chips are a single tiny die with no cooling. But of course the per-core performance is not likely to be anywhere near Xeon Phi either.

I'd consider Epiphany the simple, "slow" (per core), low power solution, with Tilera somewhere in the middle, and Xeon Phi at the other extreme (complex, fast per core, high power usage).

That said, this is speculation based on reading articles - I've not had my hand on any of the three. Yet :)