WSOY Suomi-Englanti-Suomi-Sanakirja (or Finnish-English-Finnish Dictionary) is a GREAT dictionary, especially since it comes with a CD. So I can install the CD for home use and bring the dictionary to my course and leave it in the classroom. The CD is easy to use and very practical for me.
This dictionary is complete enough for beginners to learn Finnish. The first part is the Finnish-English dictionary and the second part is the English-Finnish one. That's like killing two birds with one stone! After all, beginners may have trouble not only understanding Finnish words, but they may also need to translate English to Finnish.
What I also like about this dictionary is that it has plenty of examples of how to use the word in phrases. That way we can also learn the changes of the words when we use them in different phrases. After using the dictionary for over a year, I find that it's complete enough to find regular words, though naturally it's not easy to find slang words or other specific terms for a specific branch of knowledge, but with 117, 000 entries, it's still enough to help me understand regular words in magazines or books or novels.