NopCommerce is a very good product. Performance is very good, and most of the code is well written. I can read it like a book.
However, there are various parts that in my opinion are not finished yet, or have not been implemented.
But we don't see that as a problem because we can easily add those parts ourselves.
We keep very good track of the changes we have made to the standard code, and with a new release it will cost us maybe a day of work to merge the changes into the new code.