I'm just wondering what the most basic background knowledge requirement is for me to watch this, understand it and enjoy it. It will probably make very little sense if I just jumped straight into it, right? Also, the original OVA seems to have received quite weak reviews so I was hoping to avoid having to watch it. I know it's pretentious but I cherry-pick what I watch because there is only so much time in a day. =(
I´d say it is helpful to watch either the OVA or a couple of episodes from the TV series, else you will keep wondering why the heck this average guy is living together with a bunch of goddesses. The more background knowledge the better, but since the movie is relatively stand-alone, it can be enjoyed as such as well. And the story of the movie is taking place some time after the TV series, because all of them have angels (which are introduced in the series), so following the release dates is not really good.