As an avid reader I often need a dictionary, and as a traveller I can't really haul round my OED in my suitcase. This device, at about the size of a mobile phone, is absolutely ideal. I've been using it for over a year now and think it's only failed to find one or two words I've searched for.
On top of basic dictionary capabilities, there is a thesaurus and spellchecker, defintion searcher (you type in the key words in a definition and the dictionary finds possible words to match), numerous word games, a knowledge finder (basic dates and short snippets of information about famous personages, political movements and so on) and an 'easy to learn' list, that stores any new words you come across for easy access. You can also set up these words for use in the word games.
All in all, this is not only a purchase I have never regretted, but one that I would gladly have paid twice the price for.