Longman dictionary is great for many reasons, but I believe it needs few modifications for improvement. it has two different form of pronunciations for American English and British English. when you search a word, it shows you a lot of information about the word, such as, word family, IPA, the stress of the word, different meanings, example for each meaning, the word is an academic word or not, how many times it has been used in a sentence, and if it is a top 2 or 3 thousand written words, etc.
The problem is that it does not have an application for the mac book. The other problem is that it has the option to translate English to Japanese, Korean, and Spanish, but not to Farsi. There are many Persians living in the United States and it could be very useful to them. I am very pleased, and I highly recommend it.