I agree with Mike. However, both dictionaries do still complement each other well, even at beginner level:
- The ABC displays pinyin for pretty much all the examples given, whereas the Oxford dictionary, beyond the headword just gives you the characters and you'll have to highlight the words and characters you can't pronounce one by one (as well as work out the character breakdown, which the ABC very nicely gives you in its pinyin display). It seems a small thing, but when I was a beginner-early intermediate I very much preferred the ABC examples over the Oxford's because of this.
- The Oxford C-E is a great productive dictionary. In other words, the limited number of entries captures everyday Chinese and doesn't contain lots of obscure, rarely-used or defunct words, so it's excellent for browsing and building a vocabulary (E.g. Checking and learning all the words that a character appears in). The ABC dictionary will be better, as Mike suggests, once you start reading a lot, probably after a year or two. I found it excellent for reading for my 1919-1949 literature class, where many of the texts contained words that are simply not used anymore and which the Oxford dictionary lacked.
- Both C-E dictionaries often complement each other in vocabulary examples. Sometimes where the Oxford just gives the definition and nothing more, the ABC will have an example, and vice versa. Sometimes the Oxford entry is better used as a flashcard, sometimes the ABC entry for the same word seems better.
- Both English to Chinese dictionaries offered are similar and have gaps here and there, but together they cover most of the ground. In my opinion, they're both of value.
Basically, if you're serious about learning Chinese and willing to pay the extra, you'd be best getting the whole lot by buying the 'Complete' edition. I doubt you'll regret it. You'll find that each has it's own advantages at different stages and aspects of the learning process, while also complementing each other in many ways.
A Chinese-Chinese dictionary is likely to be offered later this year and that's one that you would be unlikely to derive much value out of until you really get into your reading.
Hope that helps you make a decision.
Ben