The makers of this franchise clearly don't believe in messing with a successful formula.
This is the mix as before – decent digital animation (this time in 3-D!), decent but by now familiar stunts (ice slides, spurting lava), a zany squirrel chasing an acorn, and a flimsy story in which our lovable heroes (grouchy mammoth, menacing but soft-centred sabre-tooth and wacky, annoying sloth) confront danger and discover some truth about the importance of family. This time, they crash through the ice to discover a hidden world of dinosaurs, plus a perky piratical weasel (voiced by Simon Pegg). It's not nearly as funny or as cute as it needs to be, but it will do as holiday entertainment for children who liked the first two and have reasonably short memories, and for adults it's more or less bearable.