Avatar's story line is an old one, similar to that of The Last Samarai, or any other boy meets girl of a different culture. Violence in Avatar is also a bit over the top, so won't be for everyone. But, in terms of special effects and creative imagination, Avatar is to 2010 what Star Wars was to 1977. By far the best place to experience Avatar would be in an IMAX 3D setting. Such a setting might be difficult to those prone to motion sickness, but it simply doesn't get any more real than that.
So, for those who enjoy an old-fashioned love story, can tolerate excessive violence, aren't looking for sophisticated characters, simply want to be entertained and can appreciate creativity and unparalleled special effects, this one is a must see.