Some changes they made I like, others I don't. It also seems like they cut out a major character...

Even if we've already seen the series before, it is best--IMO--to not spoil the events of the movie, just in case something is different in the transportion from mediums. And regardless of the direction, there is generally something different in switching from animation to live-action or vice-versa (ex: Micheal J. Fox learned this twice in the 1980's via the Teen Wolf [as Scott Howard] & Back to The Future [as Marty McFly] franchises, which had both the movies and a respective animated series), so I would just prefer to watch the movie and then judge it on its own merits, as opposed to comparing it to the animated series it is based off of.

1. The BTTF cartoon--continuity wise--takes place after the films, since not only do Marty, Jennifer, Einstein the dog, and Doc travel in the Delorean time machine, but so too do Clara and her & Doc's two sons. From prehistory to what was futuristic for the 1990's, the extended "family" certainly made time traveling a breeze.

2. The TW cartoon kept Scott's fear of being discovered (and treated like a freak ala the alien E.T.) present, but heightened it to the point that Scott seemingly hated everything around him due to the family burden--outside of the girls he crushed on, best friend Styles, his own inate athletic talents, and the sage advice his father gave in making sure that the wolven powers granted to the Howard clan were only used for emergancy purposes, following the fiasco surrounding the school principle from the film (Mr. Strickland) and the various nosy neighbors who would try to expose the hidden secret.

"This is seriously heavy." ~ Micheal J. Fox

but, Back To The Future's cartoon was based after the Movie... and it continued it, unlike the Avatar movies which are retellings of the series... so really there is no reason to bring that up. And i've never heard of teen wolf so no comment there.

And again, it's perfectly fine if you don't wanna see any spoilers. Nobody is forcing you. But some people do want.