I always use a five point scale:

1 - This movie is terrible and highly flawed. I regret watching it and would actively discourage people from seeing it.

2 - This is a seriously flawed movie but there's something redeeming about it (e.g. The premise and script are good, but the special effects are terrible or the casting is bad, or it's a mostly good movie but the lead performer is just completely terrible, etc.). I'm not recommending this movie to most people.

3 - This is a fine/neutral movie; it's probably a totally fine popcorn flick or a completely mediocre but enjoyable movie that I'll probably forget about completely a few months after I watched it.

4 - This is a good movie! This is something I'm probably recommending, especially to fans of the genre. The film might have some flaws but they're mostly minor and far outweighed by the things the film does right; this might be a mediocre film elevated by some particularly outstanding performances or a really great film that just misses a couple of marks, but, ultimately, this is the kind of movie that I finish and I'm excited to talk about.

5 - This is a nearly perfect movie; I'm likely recommending this to almost everyone, and I'll have to dig really deep to come up with flaws if pressed. This is the kind of movie that I'll still be talking about or rewatching for a long time and will hold up when asked about amazing movies.