Personally, I think an eliptical soundhole would have looked better... but up to a point, no it isn't critical. There are makers who locate the soundhole in a completely nontraditional spot, where none of the strings pass over it. I've even seen secondary soundholes in the top, between the bridge and the main soundhole. Soundholes located in the sides too. Martin doesn't do much of that. At least not yet.
