It's worth watching the original movie if you get the chance, if you like the series.
I wouldn't say the series is at all dependent on having seen it, as a prequel. There are some things from the film you can look at and say, 'oh, so that's why that was how it was!' but that's fairly standard for any prequel.
There is a reason my husband has reservations about watching the series based on having seen the movie, but it's pretty spoilery for anyone who hasn't seen the film when considered with a prequel like this one.
***=Major movie/series spoiler for those who haven't seen the film, and may not realize this going in.***