Screwdriver
Occasional Visitor
The little ARM based dev/hobby boards are a lot of fun to play with, and surprisingly useful for some... one of the nicer points is that most of them boot from SDIO, which removes a gating item for novices (brick it, pop the card out, flash the card, and back in business). One can still drive the GPIO's and what not, depends on how deep one wants to go, but if one is mostly interested in the SW side, this is easier than having to source a TTL serial cable and all the fun things there (e.g. even JTAG)..
And the price is right
I'm not sure I would consider using the Banana Pi R1 board as a full-time router, but it's a good tool for learning OpenWRT and other embedded OS's, and the cost of entry is fairly low...
One can do the same functionality with a Rasp Pi and a USB ethernet adapter, along with a cheap gigabit switch - and OpenWRT supports the Pi2/Pi3 already...
I was wondering about the Raspberry as a router. But no gigabit and the USB being 2.0 and sharing the ethernet seems like a hinderance. Might try it out as I have a spare board and gigabit switch.