(NO SPOILERS)
While I feel that the FNAF movie may not be for everyone, it is a competent film that is enjoyable, especially to fans of the franchise (despite what Rotten Tomatoes might tell you; seriously, the Mario Movie first and now FNAF?).
Plot:
The plot of the movie is actually very well fleshed out, considering the complicated lore that it is based off of (game theory has 60+ videos on FNAF, you can't tell me I'm wrong). In particular, I like development of Mike and Abby as a family dynamic, which makes it stand out as more than a "generic slasher movie". There are a few plot holes or things that may not make sense if you don't follow the franchise, but not to a detrimental extent. Also, props to the director for actually making the movie take place over 5 nights.
Acting:
The acting was pretty great overall. Not much to say, originally I was doubting Matthew Lillard but he eventually came around and did a really nice job in his role. Also, there are a few cameos in the movie... keep your eyes peeled.
Horror:
There are some relatively violent scenes in the movie, but there isn't that much gore which is pretty surprising. Regardless, while I wouldn't say the movie wasn't teeth-clenching, edge-of-your-seat scary, it can get pretty tense at some points, given that you're invested in the story.
Visuals:
The set design and costuming was probably the best part of the movie. The pizzeria, for instance, was massive and genuinely looked like a pizzeria from the 80's (think Chuck E. Cheese or Showbiz). The costuming was also superb, especially with the animatronics, which somehow were able to look lifelike yet robotic at the same time. Props to Jim Henson's Creature Shop for this one.
Music and Sound:
While I still believe the visuals were the best part, the sound design was nevertheless amazing. The music is newly composed and doesn't derive from any established FNAF-related music (except for the credits... no spoilers though), but still fits in quite nicely with the tone of the movie.
TL;DR the FNAF movie is a great movie for FNAF fans (including younger ones), and does the franchise justice despite the franchise's convoluted lore. It does have a few plot holes and may not be for everyone, but is a must see for any fans of the franchise (kind of like the Mario Movie), hence why I rate 5 stars.