I thought the way Rowling ended book 7 was perfect. It was the first time I didn't look forward to another one. She did a great job with the ending!!
I read on her website that she was thinking about doing a book 8, but it would only cover all those characters that were sort of mentioned but not actually produced in either the film or book series'. The only reason I'd purchase it would be to have the complete set. :
The most tearful moment for me was when Dobby died. That part got to me more than Sirius' or Dumbledore's death.
I knew Draco would end up being a good guy in the end, and as for Snape.. no surprise there either. But the way Rowling presented Severus was very well done. Actually, her writing style is compared to none, she is extremely unique, and I would read any other series that she writes, if she so ever chose to do so. Doubt she will tho, she's richer than the Queen of England already, and not all of her royalties have even started to come to an end.