I'd agree that Node.js is pretty dang nice for RESTful APIs. The fully asynchronous nature means really great throughput on the server, especially when most of your processing time is spent in DB or file I/O (as is often the case in APIs). As for disadvantages... I dunno. I guess if you don't really know JS very well it could be difficult to get into, and good developers are harder to find than in some other languages. But as a platform for APIs it's pretty solid.

As for a guide... There's a guide for LoopBack specifically here: http://docs.strongloop.com/display/LB/Getting+started+with+L... That framework was written specifically for writing REST APIs.