An out of office message is a compact text that conveys the most important facts: How long you’ll be unreachable, when your contacts can expect an answer, (optionally) the reason for the absence, and, if necessary, a personal note. A referral to another email address, e.g. to one of your colleagues, is often helpful or even necessary.
Yes, I phoned a dentist office late in the day for a reinfected root canal problem and got a cutsy “humphrey bogart” fake reply on their voicemail — I thought it was extremely inappropriate for a business office to use something like this. It was hard to find it funny, especially because while calling me “sweetheart” and all that, the message didn’t actually tell me when they might return my call (later that day? Next day? Next week? Never?) nor did they offer any options for emergency contact with another dentist.

While it’s vital that you get the main points across in any vacation email, brevity is important. If you’re looking for something a little more to-the-point, try this one:
I say “thanks for your message” because it feels to brusque without a greeting – but I can see it either way.