What's the intended use? If it's a wallhanging or table topper, I'd leave it as is - it's a very nice design. If it's bigger and you want to use it as a throw or something like that, I'd square it off.
I would square it up with a dark fabric (ie your black in there) and it would make the design pop even more. Its very pretty, kind of reminds me of some of the Amish designs that are bold.
as it is. i have a large table topper to finish and intend to put backing on the top and stitch, then turn right side out. very wary of trying to do binding on all those angles.
WOW its beautiful, if that's all the bigger you want it... then I would just bind it. Or no binding at all and just sew the backing on right sides together and turn it out. :thumbup: