Mudd is definitely very hard -- I've been told that it is so hard that the grads tend not to be very generous with gifts because their time at the school was always so hard. It is one of those schools that you probably do not want to be in the bottom 10-20% getting in because it would be such a grind. However, if you make it the grads do very, very well.
There are a few (or is it the same troll every time) that keep on posting that it is the same class, e.g., calculus and the same work. It makes me laugh, except some young students make actually believe him.
Stanford is the hardest school in the US (and the world) to get in to (with a bit of a partial exception for MIT/CalTech/Harvey Mudd, which have a narrower student set). The students are a lot better prepared starting off, and many of them are not taking Calc I, having done that in high school, many of them before their senior years.