Meet Dave is definitely an under-rated film, but the question is by just how much? Certainly Eddie Murphy has made some, well let's just say 'interesting' decisions when it comes to choices of movies to do. He turned in Oscar calibre work in Dream Girls, but then took a serious dive by doing the relatively pathetic Norbert (which probably cost him the Oscar for Dream Girls). Besides Dream Girls though, just what serious, or better labeled 'quality' work would anyone really remember Murphy from over the last several years? You'd have to go back to the original 48 Hours, or Beverly Hills Cop movies to find material that would generate any sort of consensus as being 'quality work'.
Murphy has turned out some family oriented, or at least youth oriented, films in the meantime including Daddy Day Care and the like, and the audience for that film seems to be the audience that is the target for Meet Dave.
The Dave that viewers will be meeting turns out to be a space ship filled with tiny humanoids that have come to retrieve a device that was sent to gather materials for providing power in the homeworld of the space travellers. The ship just happens to look like the captain who we see in the command chair, and of course the ship also resembles an Earthling which is supposed to make it easy for the space travellers to accomplish their mission while roving the planet. Nothing could be quite so simple though as the travellers have researched Earth culture from a few different sources, none of which provide a complete and detailed enough view of the world to really help them blend in. Along the way the inhabitants of Dave learn a lot about the Earth creatures and perhaps learn a lot about themselves as well.
The movie basically bombed in theatres, and seems to be flying below the radar on Blu-ray and DVD which is somewhat sad as it would be entertaining for most families. Take a chance and at least rent it and view it with an open mind and perhaps somewhat lowered expectations, you must might find it was worth the effort.
(Note that if half-stars were possible, I'd probably put this in the 3.5 range, more down in the 3 star range. I've rated it a little higher because it has been somewhat panned and under-rated, so I'm hoping the higher rating might balance out some of the non-love it may find along the way ;-) )