Disclaimer: not a writer or anything.
If you can afford to, make multiple visits - and only comment on the staff's behavior after multiple visits.
Otherwise, I look for comments on the food - if they used too much or too little seasoning, how well was it cooked, and if their meal is different (like for instance - a restaurant I went to served their burgers with cucumbers in it - it was amazing), how well do the differences complement the meals.
Knowing about the general mood and atmosphere of the place is also nice (if it's a restaurant that focuses on table eating - commenting on the atmosphere of a take-out place is not really useful. There's exceptions of course - ALWAYS let people know if a place is sketchy.
That's all I can think about right now, so that's my two cents. Might come back later.