Very well designed

I really like the built in pronunciation, the example phrases and the sheer size of the database.

I would also recommend the Word-magic unabridged Spanish/English dictionary.

Rather than say one is better than the other, I think they compliment each other and the combined number of words you will cover 99% of the spanish vocabulary and only occasionally you may have to resort to the word-reference site for some localized slang.

The cost of both together can seem high, but if you are serious about studying the Spanish language, you will be using both daily for years.

wallroof about Collins Spanish Dictionary, v2.0