Ted is not The King's Speech, it was never going to get across the board glowing reviews. If it wasn't polarizing, I imagine Seth MacFarlane would've been disappointed. So, not surprisingly the critical reception has been mixed – 59 on Metacritic and 67 on Rotten Tomatoes – meaning we might need to dig a bit deeper into what people are saying.
Mostly all reviews, positive and negative alike, agreed that fundamentally the film has one main joke, which as A.O. Scott wrote it in the New York Times: "A toy bear comes to life and turns out to have a filthy mouth and a taste for weed." Beyond that, how much the critics liked the movie seemed to come down to how much they bought into MacFarlane's crude, reference-heavy, Family Guy schtick and how much they bought into the plot of the film, which apparently exists.
Roger Ebert was fully onboard, calling Ted "the funniest movie character so far this year" and adding the film had the "best comedy screenplay so far." But mostly he loved that bear:
What's remarkable about "Ted" is that it doesn't run out of steam. MacFarlane seems unwilling to stop after the first payoff of a scene. He keeps embellishing. In Ted, he has an inexhaustible source of socially obnoxious behavior and language, and it's uncanny the way a teddy bear can get away with doing and saying things that we wouldn't necessarily accept from a human character. This is partly because Ted is a stand-up insult comedian trapped inside the body of a teddy bear.
The New York Post in its glowing review loved the bear but seemed to love the the story more:
Yet the surprise of “Ted” is that it goes for honest Spielbergian wonder, too, and even earns some tears. Though you’ll be able to say that you were merely crying with laughter at the filthy jokes.
A.O. Scott was not as affected by the fitlth or the sentiment:
Tolerant amusement is pretty much the best this harmless little picture…is able to manage, even though it strives for obnoxious hilarity. The sin of “Ted” is not that it is offensive but that it is boring, lazy and wildly unoriginal.
He takes this a bit further:
There are some genuinely, wildly funny bits in the movie…but the feature film is not a hospitable form for Mr. MacFarlane. He has no particular visual knack, little interest in storytelling and nothing better to do with his naughty bear besides stuff him into a soft, sentimental comedy that seems almost proud of its lack of wit or conviction.
Man, when A.O. is on a roll, it's frightening; however, his poetic flourishes might overstate how noticeably bad the storytelling is. Ann Hornaday in her fairly negative review for the Washington Post might ultimately have put it best:
The problem is that MacFarlane’s sneering, jokey humor and wearyingly coarse toy character can’t sustain interest beyond that initial outrageous guffaw. And a third-act plot twist feels like padding rather than motivated by genuine narrative — wait, I just remembered this is a review of a movie about a talking teddy bear. Come to think of it, “Ted” may be best enjoyed while enjoying the same mind-altering substances its protagonists ingest in such copious doses.