An electronic dictionary is almost mandatory when you get to a high level of Japanese but it can also become an hindrance for beginners.
To begin with, what's in an electronic dictionary? There's around 100 dictionaries, manuals and guides (on how to write letters or use keigo...). For example in mine (it's a Casio EX-word XD-D7200) there are bilingual and monolingual dictionaries in French, English and Japanese. There's also the Britannica Encyclopedia (English and Japanese versions). And a lot of other stuff but it'll take too much time to name them all.
All the recent ones have a touch pad and a touch screen to directly write the kanjis and an audio system (that way you can listen to example sentences and pronunciation of Japanese accents like in the NHK accent dictionary). I can use up to 2 microSD cards and there's an USB cable to transfer files from your PC. It usually works on LR6 batteries.