It can come in handy for secondary students. I remember that when I started learning Japanese many years ago, I bought one pocket dictionary from the publisher, Kadokawa Shoten. At the time there were no iPads or apps to download. It helped me to find the meaning of a particular words in a short period of time. But once you get to more advanced levels, you will find sometimes the pocket dictionary may not always show or express the application or meaning of a particular words as it is used in real life. I’m sure they are improved now from my time.
Now there are several online dictionary resources you can use for free if you have internet connection. It is recommended that you use at least 2 to cross-reference when looking up a word’s meaning to be sure.
The pocket dictionaries is useful but will have its limitation as it’s ‘pocket’ version and may depend on the author and publisher’s choice for a particular word.
P.S. Please click here for online dictionaries.