Ok, so i'm actually running a pretty large store on Django Oscar. But i would say that it really depends on what you are building
The only reason i choose Django oscar over something like shopify is that we sell a highly customizable product and needed total freedom to try out different ways of giving discounts and creating vouchers. If you just sell standard products then don't bother.
I will give credit to the creators of Django Oscar for building a highly customizable framework and if you know your way around Django, the overhead of using it shouldn't be too large.