We saw it the other day and thought it just o.k. too. Not bad, not great. It was visually very appealing, the storyline did seem to go on a bit too long. Ellen DeGeneres was terrific, as was Albert Brooks, and so perfect for the voices of Dory and Marlin.
(perhaps the lack of music may have made it seem longer? I always like Disney movies that have a soundtrack to go with it)