We did this last year and LOVED it, cannot wait to do it again this year!
The food wasn't great, but then again, I've never really had excellent food at a character meal anywhere so personally it was to be expected. The scareactor interactions totally made it up for it though, Chance came by our table a couple times to take pictures and was so, so sweet! I know they've had different scareactors each year so I'm excited to see who'll be there this year-but I'll definitely miss Chance!
I don't remember what time our reservation was for. But the park was still open (I believe) to day guests as we had to check in near Blue Man Group then get escorted by a TM to the restaurant. The entire dinner experience kept us in there for roughly an hour-hour & halfish, by the time we got out though we were able to walk right in to The Exorcist.
Overall it was a really fun experience and I highly recommend trying it!