Yeah, that’s all I need to know when I’m trying to contact someone who’s out. 1) When you’re coming back so I know if my issue can wait, and 2) Where to go if I decide that it can’t.
I might sound nitpicky but the language is important. “Might” or “may be” or “slower than usual” are vague and don’t offer the sender all that much information about when you’re really going to respond to them. Worse, they do a horrible job of protecting the time of the email receiver who, as the responder notes, is not in the office! Such a responder implies that, not only will the vacationer reply to the email, but they may not even miss a beat. They may be slow to respond, but they also might not.

I think that it depends on whether or not that OoO was going to people in the company, who new your personsality and would appreciate the humour/personal touches, or to everyone, always. If I got the from OoO from a quirky co-worker, fine. It I got it from an outside contact that I have had little contact with? Unprofessional and a bit off-putting.
A new survey undertaken by YouGOV of 1,000 Britain-based office workers has revealed that 30% of employees believe their workspaces are outdated and uninspiring.