We open on a gnome in front of a red theatre curtain. He says: "The story you are about to see has been told before. A lot. Many times. But we will do it differently..."
This much is true. I watched an interview with the film's director Kelly Ashbury, who states that the first two acts are 'beat for beat' the same as Shakespeare before it veers off. And certainly, we meet two households in Stratford-upon-Avon, both alike in dignity, with rival gnome collections in their back gardens. When the elderly single male and female bickering neighbors leave their house every day, the gnomes come alive and engage in their age-old red versus blue feud and drag-race lawnmowers. One day blue Gnomeo bumps into red Juliet in a nearby garden, they fall in love, are separated, Gnomeo engages in an argument with a statue of Shakespeare (voiced by Patrick Stewart) over whether a happy ending is better than a tragic one, and then it meanders around until it stops, happily ever after.
Gnomeo and Juliet has a stellar cast of voices, ninja gnomes, er, music by Elton John, and, um... I'm sorry. It's no good. I tried to like it, I really did. But it was, by turns, misogynistic, racist, homophobic, xenophobic, cheap, and dull, with jokes about women, gays, and foreigners that I thought we'd done with decades ago.
There are some okay gags in it: a laptop computer used to order a new lawnmower has a glowing banana on its cover; there's more gnome jokes than you can think of, ('rest in pieces' and 'bless her to bits' when a dead gnome is remembered), not to mention a fair few Shakespeare in-jokes (as Juliet tries to keep a dog out of her garden she shouts 'Out! Out!' just before the owner can be heard crying 'Damn Spot!').
I should add that while it's not ugly, it isn't particularly pretty to look at either, nor does there seem to be any real benefit from the 3D effects (a ticket for the regular version was about half the price, and I couldn't see how the 3D Experience doubled the value).
So I'm struggling to think of who would want to watch it. Is it as beautiful to look at, as witty, charming and heartbreaking as Up? A springboard into the world of Shakespeare for kids while entertaining adults, like Baz Luhrmann's Romeo + Juliet or Shakespeare in Love? No, no, and no.

Touchstone Pictures
If it was a rainy weekend morning, and I wanted to take my nephew to the movies, have him be entertained by a lot of gnomes running around doing things stone figurines don't normally do, then I suspect it wouldn't do any permanent damage to his development in life—but equally I doubt it would provoke a sudden fascination with Shakespeare.
Early on, Juliet is given a pampering before her first date with Gnomeo, and masking tape is used to wax her legs and upper lip; she later gleefully relays to her frog friend Nanette the size and pointiness of Gnomeo's hat (the mark of true gnomic masculinity). Then as gnome Benny trespasses into the woman's house, he somehow ends up inside one of her old, oversized, grey-ing bras... I suppose these vague sexual references are being dropped to entertain the older members of the audience, but we found them just plain weird and slightly disturbing. Judging by my companion's face, this is not a date movie either.