Can I ask why nobody likes 50 shades? I'm trying to figure that out. Also, should I read the trilogy then watch the movie or just watch the movie?
I wouldn’t say that nobody likes 50 Shades, it has a big fan base. There are just a lot of haters because it’s controversial. Not everyone likes to see a sexual topic like BDSM presented so openly and explicitly in the mainstream. Also, many things in the books/movie can easily be interpreted in different directions, so those who dislike 50 Shades find a lot they can complain about even though it may have been intended differently. Another thing that adds to the negative reception is that it originally was a Twilight fanfiction and, quite honestly, is not a literary masterpiece. It is the same here as with Twilight. It is very polarizing, kind of a “love it or hate it”-thing. You see, the more people are passionate about something that is controversial and/or has not been perceived as “good” by critics or the media, the more people are going to hate on it. There is a constant tension and the reactions are more extreme, the more exposure the thing has gotten in the media. Long story short, people like to complain and hate on things and they are just looking for the biggest and easiest target. Everyone is entitled to their opinion, of course, but things can get ugly pretty quickly.
As for your second question, you can do it either way. If you read the book or books first, it will fill some gaps and there are moments where knowing more backstory is quite nice (it’s little things that people who have not read the books wouldn’t even notice). Especially in this case it might be helpful to have a little more insight into the characters and be aware of a few more things that happened that didn’t make it into the film. But, there is no necessity to have read the books in order to understand the film and you can always go and read the books after you have seen the film to make all the connections and have a different experience with the film a second time.
I usually like to see the book and the film seperately, because they are different art forms with different parameters. Since in my humble opinion, there is no definite “the movie is better or the book is better” there is advantages to any way you choose to tackle FSOG. The book by itself is fun, so is the movie, but the book does complement the movie in certain ways and some things are definitely better in the movie. I guess it depends on what kind of person/reader you are and how open you are to changes.
I’m not sure if this helps you, since I am not giving you a “you have to do it this way”-answer, but I hope my rambling, uhm, elaboration :D, does help a little. If not, you can always message me again and I will probably give you an “I would do it that way”-response that I’d need to think about for a moment :)