The only other change I made was to cut an extra set of ties (i.e. 4 pieces instead of 2) so that I could sew them together and turn them right sides out. the pattern simply has you cut two and hem the edges - since the wrong side will show when you knot the ties and wrap them round your back, I think it is neater to do it my way unless your fabric is particularly bulky. I also left off the thread chains in the side seams to hold the ties in place, they just don't seem to really be necessary.
Finally I have a sewing with knits tip - do not be lazy and try on the top with pins in the side seams when checking the final fit before permanently stitching. I did and while I was machining the seams felt my arm stinging and was horrified to look down and see that I had managed to do this!