I think most people today realize the impact the French Guillotine can have on a show. The Guillotine acts as a very decorative piece of furniture especially for a Halloween show and (depending on presentation) can close a show.
The French Guillotine is a natural for comedy, and many magicians use the effect that way, getting ready to trip the wire so to speak, but stopping at the last moment as the crowd howls and the magician begins to digress.
Couple issues, the prop is heavy, not matter which one you get. Also, when compared with the larger guillotine illusions the French Guillotine really doesn't look that scary. However standing by itself it certainly looks scary enough. Several performers I know shy away from this effect because they consider either the effect politically incorrect or asking a woman kneel on a stage is not polite ( I think at Halloween political correctness and politeness is sometimes put on hold but these issues are worthy mentioning). Although the prop is inexpensive compared to the huge stage guillotines which cost thousands, you are still going to shell out $500 -$700 for one of these new (They are somewhat plentiful and have been around for ages so sometimes you can pick one up at a magic flea market or magic auction).
The French Guillotine folds at the middle to make carrying it a little easier. Putting this effect on rolls might not be a bad idea either (there is an article explaining this in detail during mid September 2011 Halloween Special).
The effect could not be easier to perform, you can make it a little spookier by having a skeleton drop the blade using a piece of thread, and this effect comes highly recommended. I don't know anyone who regrets purchasing a French Guillotine.
Remember most of this effect is presentation, the actual effect last's about a second as the blade comes down. I have seen this presented very well and I have personally seen some mistakes in presentation (One that comes to mind was a performer doing a reasonably good job of presenting this, but went a little too long and the small girl in the guillotine began to get nervous and started crying).