Sora no Otoshimono Movie: Tokeijikake no Angeloid 1 is a sequel and recap of the Sora no Otoshimono series. So, we basically get to see everything from the previous two seasons and perhaps the manga itself from a character's point of view. If you had seen the two previous seasons, you could watch this movie but you won't really expect anything much. Just note that this movie has parts and this is just the "first part". It is also not considered "season three" which is coming soon. Besides that, the graphics are quite updated and the scenes are just about the same from the previous ones. I don't have much to say about this movie but there are some parts that are "unseen" from the previous seasons. So in conclusion, there is nothing much about the movie besides the recap and a little bit more details.
But, if you haven't seen the previous seasons and perhaps at least read some of the manga, I suggest you to do so before you attempt to watch this movie and before the third season comes out. The series is very entertaining and don't forget that this is an echii, action, harem, and comedy show. Though, don't let that put you down even if you're not an echii fan. This series is just quite good.
Conclusion: A movie recap and more details added from the previous seasons and perhaps manga from a character's point of view.
Need to watch this quickly before the third season gets a release date. They already announced it, but I haven't been feeling up to watching another movie yet :P
Lol, you don't have to unless you want to waste some time.