Good, funny, but could be more.
Haruhi Suzumiya has likable, funny characters with their own unique personalities and quirks. This is most definitely the series's biggest strength, as they are most definitely endearing to the audience. The two principal "main" characters, Kyon and Haruhi, gradually recieve a generous amount of character development. The problem is that some of the other characters tend to be left in the dust.
A good example is Mikuru. Through her future self, we learn who she will become, but we are not able to observe her actually developing in real time. In the majority of the show's episodes, she seems to exist simply to get molested by Haruhi again and be a rather creepy sex object for Kyon.
The series has an intriuging premise. Haruhi being a Reality Warper
and a borderline god has a lot of potential for storylines. When it is used, the plot tends to take a slightly more Sci-fi styled direction. I will say that I preferred this direction for the plot. The six part "Melancholy" arc heavily utilises this element of the plot to great effect, with interesting concepts and effective drama. However, I feel that this is normally underutilised In favour of admitedlly funny slice of life fare.
The first season is overall good. After the opening six parter though, the sci-fi and dramatic elements seem to fizzle out. This is disapointing but the rest of the season is still good. Unfortunately the second season, after a great premiere episode, is half made up of one episode reanimated over and over. And the rest of the season still does not feel up to the quality of season 1. Overall, a large disapointment.
And then, the film. Disappearance contains pretty much everything I expected the series to be. A large amount of characters have a reduced role, but the plot is dramatic, emotional and has the sci-fi bent that I feel the series should have leaned further towards. There is some wasted potential here. The series cannot seem to decide what it wants to be.
Overall, after 1 good season, 1 disapointing one and the film, the good balances out the bad. I would reccomend this show as a whole, despite it's flaws. Just don't bother watching all of Endless eight.