The idea of combining dictionary and thesaurus has become a popular one recently, and the big publishing houses have their own versions. I repeatedly argue that everyone should have a decent dictionary and thesaurus to hand, so combining the two seems to kill the proverbial two birds.
It also, of course, increases the size of the one volume. You need to ask yourself what use you intend making of your dictionary / thesaurus. You may find it useful for crosswords - and, depending how sophisticated the crosswords are, the more sophisticated your needs will be. You may need a decent dictionary and thesaurus because you write - for profit, for pleasure, as part of your job, or in the course of your studies. Your decision then might be influenced by how portable the book is, how wide a vocabulary it covers, etc.
The "Oxford" is quite a big, heavy volume. It's definitely not suitable for lugging around with you on your travels. It's also a bit on the big side to fit conveniently on a desk top or inside a drawer; it tends more towards sound reference material, to be kept on a bookshelf. And it is definitely too heavy for small children, and may be a bit awkward for anyone with, say arthritic wrists.
Organisation typically follows a pattern of having the dictionary element at the top of the page, the thesaurus below. This means you have to get into the habit of looking for words in two places - and you will find an element of duplication of definition, or repetition of synonyms occurring because of this.
Oxford's bonus is the inclusion at the end of a 'Wordpower' guide - a sort of anti-thesaurus, which takes a range of key words and links these to many of the concepts or words with which they might be associated. So, it lists "war" and offers as one of its associated words, "ceasefire". It's an interesting concept, and one which has evident educational value if you are trying to study the language or help someone else do so.
Printing is, as usual, excellent - though it is on the small side and you may need to wear your glasses. Paper quality, too, is robust, with a quality feel to it. You sense this is a book designed to last. The scale is commendable - it covers a huge vocabulary and it would have to be a pretty obscure word to miss inclusion. What you don't get are the extensive etymological and historical notes on word origin which you'll find in, say, the "Oxford English Dictionary". But, "you pays your money".
All in all, an excellent reference tome for the serious writer, and one which many homes would treasure. But, I always argue that you should go to a bookshop and take a look at the book in the flesh. You know why you want a dictionary or thesaurus, or combination. But it's a very personal choice - and a very competitive market. Oxford offers an excellent volume, well worth considering, and one which I personally endorse and value.