First of all, hello. Second of all, if you're here to know whether you should watch this movie or not, I'll tell you this: if you liked the series and want a better conclusion, yes, yes you should. If you just liked the series, still watch it.
For those of you who don't know what the endless eight is, it's a story arc in the original light novel that lasted a fairly short amount of time. No longer than many of the other short arcs, at least.
The first scene of Haruhi Suzumiya already begins to set the mood for the entire series and the subsequent episodes in the first arc.
For the few of you who don't know what Haruhi Suzumiya is, I honestly don't know how that's so. I've known about this series for about as long as I've known what anime even was. It's just one of those shows that pop up in discussions for seemingly no reason every now and then.