My YA son and I read this together at Christmas, because we've seen and loved so many film versions of the story. This was an engaging version, and we usually read longer than planned because we didn't want to stop.
The language was definitely more modern and direct, but not childish. The imagery could also be modern, but rarely jarringly so (comparing a scene to a the flickering images of a movie projector?!).
I compared various moments to the original, and found that the adapter had added Scrooge's emotional and physical reactions, whereas Dickens had simply described what Scrooge had seen and what he said. We generally liked these changes, which isn't to say they are exactly an improvement over the original (which we haven't actually read yet). One change I didn't like was describing Scrooge tormenting a rat by stepping on its tail and poking it with his foot or something. I felt that gave him a psychopathic vibe that wasn't fitting.
This version also included a couple scenes that we don't remember seeing in various film versions (visiting a mining camp and a lighthouse). These scenes and the reactions I mentioned earlier made the story feel fresh even though we had heard it many times.
I definitely recommend this version for young and old!