I do lots of recs on my journal and I tend to be honest. I don't rec anything I don't want to read again; in fact, my recs are a way of keeping track for myself stories that I like well enough that I'll go back to them in future. So I generally offer a teensy, mostly non-spoilery plot synopsis, what I liked, what didn't work for me, and quote or two. Rarely, I do a review of a fic that's a post in and of itself and I tend to go into more depth about what didn't work for me in those.

As a reader, I prefer honest reviews and as a writer as well. More often than not I find complaints about my work legitimate and have either revised or taken the issue under consideration for future works.