It's not too dissimilar in principle to the Gamebuino in that it's a small, open source hand-held console that encourages community written games. I really like this approach above emulation, as it's closer to the original philosophy of programming from when I was young. When you were writing a program, you were also in control of the hardware directly, without many layers of software abstraction, SDKs and high-level programming.
The benefit of Pimoroni's 32blit over the similar Gamebuino is that development with C++ is supported easily (rather than rather clumsily behind the Arduino API), it's larger and hopefully more comfortable for adult hands. And the screen looks fantastic!
They have already added one stretch-goal which was to add to the library of assets available for programs written for it. This is also encouraging, as I can't help feeling that there will be a whole gamut of games written quite quickly as obtaining sound and graphics for games is often the lengthiest aspect of development.
We're yet to see more details of what developing for the 32blit may be like, but I'll try to post more as info is made available.