I suppose, when I see a version of The Grinch made by Illumination, I expect something akin to Despicable Me. We do, after all, have a misanthropic protagonist who is changed by the film's events to make him more friendly towards the world and especially the happy little kiddies. I also, however, expect that to work on more levels.
The Grinch does seem like a perfectly satisfactory kids' cartoon with a few silly pratfalls and physical gags to prop up a story that could be told in twenty minutes. What it is severely lacking is anything to keep the adult viewer engaged with a plot that we are now all too familiar with.
As in the Ron Howard/Jim Carrey version, there is some attempt to fill out the running time with a Cindy Lou Who subplot and a bit of backstory for why the Grinch is so grinchy. Neither element really gets past step one though, and they seem much more interested in filling time than actually developing the characters. The Grinch doesn't like christmas because he had a shit christmas when he was young (because he was an orphan and nobody cared about him). Cindy Lou has a very special christmas wish because she's one of those nauseatingly selfless and aware six year olds that you only get in films.
The character and plot are all just a little bit too thin and the whole never manages to feel like more than a handful of sketches strung together. The physical humour allowed for by the animation is done pretty well and has some inventive elements. There are a few laughs to be had with the Grinch's antics with his dog and reindeer sidekick but if you've seen the trailer then you'll be familiar with most of the better moments.
The cast are fairly solid as you'd expect, though nobody stands out from the crowd either. Benedict Cumberbatch is obviously the flagpole signing and he does an admirable job without breaking any new ground. There are a couple of scenes that only really feature the Grinch grunting or making generic noises, which does make me suspect that these were written later to pad out the runtime and they couldn't get Cumberbatch back in. This is in keeping with the piecemeal nature of the film where you do feel that there are chunks that could easily be slotted in or out without any consequence.
Pharrell Williams provides the narration and the film suffers greatly for this. It's a voice that is lacking in gravitas or character or anything really. You had Angela Lansbury in the recording studio, why not get her to do it?
Overall, the film provides enough little comedy moments and visual elements to keep the average seven year old pretty well entertained. Seen as a kids' film then it does the basic job you'd expect. But for a more discerning audience, you will be left hungry for something more satisfying.