I've never read a parenting book quite like the Oh Crap method. Firstly, the author claims if children aren't night trained by 3 and a half their bladder begins to entrophy - isn't this total rubbish? I thought a hormone dictated whether children could stay dry overnight. Likewise, the author claims if you leave potty training til after 30 months you're setting yourself up for real problems, but anecdotally I know plenty of people who have trained at 3+ without a problem.
I also find the author's style rather abrasive and hectoring. She says in an early chapter (and I'm paraphrasing here) that if you're waiting until your child is ready, you're just putting training off and implies you're lazy and just need to get on with it. She also later literally says don't come crying to her if you decide to skip the commando stage and have lots of accidents. Most parenting books are a bit more supportive and diplomatic?!
I'm not saying there's anything wrong with her method, I'm using it myself, but she doesn't sound like someone I'd want to go for a drink with in real life 