I'm an English as a foreign language teacher from the UK. This is an excellent dictionary for intermediate and advanced learners of English.
The definitions are clear and the example are useful. I think it would help learners, if they included questions with the idioms in them. I always include questions in my free English vocabulary email lessons for busy non-native speakers who have studied English for several years. I think questions are very useful to help deepen the learners understanding of the meaning.
It's really easy to find idioms by just looking up key words in the idiom you are trying to understand.
There's a really good section called the "Idiom Activator". It helps you find idioms by concepts. Unfortunately, it only has ten concept areas. It would be really useful if they expanded that section.
But overall I would strongly recommend this dictionary for intermediate and advanced learners.
Paul Snookes. english2U.com Bringing People Together Word by Word