I received this edition (ISBN 978-0-19-922874-4) of Gareth King's "Modern Welsh Dictionary" as a replacement for the earlier edition (ISBN 0-19-864531-7) of a slightly different title "Pocket Modern Welsh dictionary", and am delighted with it.
Slightly thinner and lighter than the previous edition, it is actually more "pocket-sized" despite losing that part of its name, however I have been unable to find any difference in content. One nice addition is the shaded letters on the edge of each page that are helpful in finding a word quickly by going rapidly to the section of words beginning with that letter.
I only gave the previous edition 3 stars as the pages started to fall out within a couple of hours of starting to use it, however this version seems more sturdily constructed so I've given it the full 5 stars.
Although I've not been able to find some words in it when trying to translate a Welsh text to English (if there were more words, it would obviously be a bigger book!), there are excellent examples of usage for most of the words which is a great help for me as a beginner. There is a brief grammar guide and mutations are indicated where appropriate - again, a huge help for a beginner - as are gender and plural forms.
I've supplemented it with Collins Spurrell Welsh Dictionary (ISBN 0-00-719658-X) which is much more of a pocket dictionary and has over twice as many words in it, but only the bare translations so there's still uncertainty of translation. For example the English word "bow" is translated as "bwa" or "dolen", but are these a prettily-tied ribbon, the front of a boat, or the thing that fires arrows?
As a new learner, I'm finding the two work well together, but if I had to manage with only one, it would be Gareth King's book.