Smashwords was really easy for someone like myself to use - what I know about tech you could write on the back of a postage stamp!
I would agree that there needs to be more characters allocated for book descriptions.
From what I have been able to see, my book has converted OK, however there is no way of my knowing what it looks like to other people on their ebook readers. It has been approved for their premium status so I presume that it has converted well?
I have a few writer friends who had been using Smashwords for a while and who also distribute their books directly with Amazon. As far as I am aware, they will be better off when they distribute to Amazon via Smashwords.