The first two reviews are mixed, but MR comes out of them OK.
The Times' critic calls the play "pretty dated" but "good, harmless fun". He calls MR "charismatic" and says he has "plenty of opportunities to loom, domineer, and, on occasion, splutter, snap or madly cackle. He looks like a vast, sinuous snake, menacing its prey - but, sadly, not like Karloff, who created the role in 1941." http://www.timesonline.co.uk/article/0,,685-591903,00.html
The Guardian says "...not even the presence of Seinfeld star Michael Richards as a sadistic killer can reconcile me to this bag of old bones...I couldn't help feeling that Ealing Studios did this kind of poison-in-jest comedy with infinitely more style" buy adds that "Richards lends Jonathan a cadaverous intensity". http://www.guardian.co.uk/arts/reviews/story/0,11712,903258,00.html
You may have to register to read the full reviews - I have not posted them here as they are long and somewhat OT.
Ian