I am not sure whether more episodes would have made a difference or if a quick end is the best. Things are just so rushed and there are so many leaps in storytelling:
....but in the end I am not sure the writers had the chops to keep this going and end it more completely. You can only live off a better talent (GRRM) and his story for so long. It was his brilliance that brought this to life and IMO it needs to be his brilliance to end it. I felt once the show strayed from the original books for good it was never on solid footing. It had great moments and some of the episodes were good/great, but there have been some others that were just filler at times.
Don't get me wrong, the show has been great and has put faces to the names I have read about for many years. It has added to the drama and intrigue the books weave so well. I am glad HBO produced it and I have enjoyed it.
In the end, maybe I am just having problems with it coming to an end in a less than satisfying way. Not sure what I want, but this isn't it.