This isn't as tedious as it might have been, thanks to some clever design decisions. The pixie you've just freed floats alongside Wario, carrying an arrow sign which always points towards the correct path - so you don't end up backtracking in the wrong direction. In some levels, there's a machine for super-charging Wario near the pixie's cage. This means that with decent reflexes and an eye for when to jump, you can race back through the the whole level at top speed - effortlessly barging through enemies and obstacles as you go. Which is fun, obviously.
Another plus point is that you don't follow the same route back through levels; new pathways open up and there are different obstacles to overcome. This creates a problem for completists, however. If you're the type who likes to seek out hidden booty (and there's plenty here), you can spend ages trying to work out how to access a particular area or break a certain block - before realising it's only possible on the return journey.
Perhaps you're not a completist, and just want to run through levels at a quick-smart pace without worrying about secret treasure chests and hard-to-reach bags of coins. In which case, you will also end up with a problem. Accessing new sets of levels isn't simply a matter of completing the preceding ones; you must buy a map for each area before you can visit it, and you can only buy maps if you've collected enough coins.
The first one's cheap, and you'll have earned the asking price just by racing around, but later on they get more expensive. You may have finished five levels and beaten the boss, but unless you also made a bit of effort to find hidden goodies, it's a question of repeating levels again to get more coins. Considering you've already been through each of them at least twice, this isn't much fun.
Issues like this prevent Wario Land: The Shake Dimension from crossing the line between good and brilliant. It feels as though the game has been designed to please both hardcore and casual players, but it fails to satisfy the needs of either group.
Fans of classic platformers will find most of the game too easy. Nintendo has tried to make up for this by sticking tons of bonuses in the most fiendish of hiding places, but the dual pathways can lead to confusion. This won't be a problem for those who like a lower difficulty level and faster pace, but they'll likely end up frustrated by the trickier spots and enforced repetition.
It's a shame, particularly because The Shake Dimension could have been the 2D platformer the Wii's been waiting for. The shake mechanism works well, at least in some instances. The production values are extremely high; the visuals look hand-painted, the animations are superb and the music is great, in a nineties way. There are flashes of retro brilliance such as the Egyptian and submarine missions, clearly inspired by classic Game Boy title Super Mario Land. But they are only flashes.
Does Nintendo still care about hardcore gamers? This title could be used as evidence for the defence; it's a 2D platformer, with hard bits and boss battles and rewards for extra effort. But, as the prosecution might point out, even here there are indications of an attempt to appeal to a wider market. The result is a game which is good, but not great, and certainly not up to the standard of Nintendo's best 2D platformers. They don't make 'em like they used to, that's for sure. Still - at least they make 'em.