I recently purchased ‘A Dictionary of Japanese Particles‘ by Sue A Kawashima. So far I am pretty happy with it. I am a Beginner (I just sat the JLPT4) so many of the particles I have not even seen yet. But the ones that I know and have read through, seem to be thoroughly covered. The examples are fairly extensive and at a good level. I don’t understand a portion of the vocabulary, but it is easy to pick up due to the translation (ie, you don’t need to flip to another dictionary for the word meaning all the time).

A Dictionary of Japanese Particles
I was initially annoyed that the examples also had a Romaji version, but it is not too bad. Many of the books I looked at have Romaji, some exclusively so. I am guessing the publishers are doing this to make the books more user friendly, and less daunting for new learners. Some learners might not even want to learn to read. But for me (who wants to learn to read), I find the Romaji an unnecessary distraction at best, and a inhibitor at worst (when it replaces Hiragana all together). But in this Particle dictionary, it compliments the Hiragana by providing additional information like work spacing and word type markup (nouns and adjectives for example). But I would still like to complain about the Roman index. We are learning Japanese, so why is the index in the Roman Alphabet? – I guess for the same reasons as above. Oh well.
It is a good size for studying too – the size of my hand. It has exercises at the back of the book which would be good for JLPT4 and 3. After that I am not sure.
All in all, pretty good.