The Mitchell book is definitely showing its age these days. It's not terrible, but anyone thinking of buying it should be aware that it is a broad but shallow tour of machine learning as it stood 15 years ago, and machine learning as a field has changed significantly since then. Most notably, there has been something of a Bayesian revolution that Mitchell basically ignores (understandable since the book predates it).

Don't take this as a recommendation, because I haven't read it, but Stephen Marsland's Machine Learning book appears from a glance at the table of contents to be a much more modern attempt to provide the same type of coverage as Mitchell. But again, I can't speak to its quality.

Chris Bishop's Pattern Recognition book is also very good, but it's not the same sort of book. Bishop is exhaustively deep on the narrower range of ML that he covers, but you won't get the same sort of coverage of the wider view of the field.