How do you write a review that low-key says a movie sorta sucks, but is nice?

Basically watched a almost micro-budget first-time feature with young actresses that had too many messages, all of which were valid but under-developed so they all sort of fell flat because none of them got enough focus or quality. Nothing about it stood out at best.

I would love to see the director's second film, and possibly even two of the lead actresses in a now more experienced role. The whole thing was a disappointment and kinda messy though.

I know I'm not going to make or break anything, but it was a film with a lot of hype and it did not get many reviews, and I do think I might influence some people by virtue of being one of a few opinions.

What are some framing devices you use to not LIE, but to be constructive in a situation where a review doesn't need to be harsh?