I got one at home for a review and here's my conclusion in short.
It's available with maple or rosewood board and with an alder or mahogany body. I got the rosewood/alder here.
First: It looks a bit Gibson doublecut (and Rick 3000) but it isn't Gibson sounding at all. With a bolt on maple neck it will always be more Fender than Gibson. The body is light and it has a narrow neck, like most Mustangs (the JMJ and some others have fatter necks, but it's more J-ish), so it's veru comfortable to play. Like the DC Jr. the pickup is easy usable as thumbrest.
It has a push/pull. In the normal setting it's more like a good Mustang. Sanberg even claims in a document which goes with the bass, it has a split-P sound. When you use the P/P the full humbucker kicks in. You lose a bit of top end, but you gain a lot of low warmth. Very nice for three piece rockbands. It sounds big, the high on the board runs sound very fat and I like it. No Gibson fatness and sweetness but a ballsy Fender.
I once reviewed the pawnshop Wide Range Humbucker competion Mustang, that was many moons ago, but I remember a similar sound.
The bass is very well made with Sandberg's own tuners, control knobs and bridge, it has a light aging and all looks very well. Any complaints? No. I would like to try the mahogany bodied one too, but I think the maple neck makes more difference. I like the tone of this rosewood board one.