The/a curate’s egg

Pro Tip 1/3

Use when something is neither entirely good nor bad, but has mixed aspects.

This budget hotel was a curate's egg, with clean rooms but unfriendly staff.

Pro Tip 2/3

Originates from a British cartoon; may be less understood outside the UK.

I explained my British colleague's 'curate's egg' reference to our international team.

Pro Tip 3/3

It suggests a polite or diplomatic way to criticize by acknowledging some positive aspects.

Your article is a bit of a curate's egg: great research but with unclear conclusions.