I have connections with all of my music partners cant live without them. The 1680 is a great machine that I've found very easy to use. Manual is mediocre-good, any problems I've had have been cleared up reasonably quickly by their support staff. Definetly would advise creating your own abbreviated manual to save time.
Most functions become very easy.
For the money I think the effects are very good, awesome in fact. If all you had was the internal effects you coul still make very pro recordings. COSM guitar sounds are good enough for non-integral guitar parts and have inspired some wacky alternatives. The possibilities for this machine seem endless to me if you take the time to learn the manual. If you purchased one or two other pieces of equipment to use with the 1680, I would recommend a mixer or mic preamp, and a compressor.