I love them! We've done a few now, all out of boxes. There is How to Host a Murder, Murder a la Carte and Murder Myster Dinners (at least over here). Of these How to Host a Murder are the best - the attention to detail is better, and the murderer doesn't know they are the murderer till the final round, so everyone is kept guessing. One I did I knew I was the murderer from the start and it just wasn't as much fun.
The best ones have been the ones where everyone is into it and makes an effort to dress up etc. There was one I went to where I'd dressed up and a couple hadn't bothered and sort of rolled their eyes at me - that one was a bit of a flop LOL.
If you do it, keep the food simple! You will be trying to follow the unfolding story, answer questions posed to your character, etc. and the last thing you want is to be preparing Michelin food while it's all going on.
Oh! And be prepared to match theme to weather. Sounds strange, but we did one set in Egypt or somewhere in Victorian times so we were all dressed up to the nines with bustles and high necks and heck knows what else and it was 80+ degrees outside! To say we were hot is an understatement!
I'm planning on doing one for friends soon, and DD wants to do an all-girl teen one for her birthday party, so I think she has the bug too.