If you're not the type to solve all the puzzles on a given map, it's probably not worth it at full price. There's 82 levels, with each having 3 items to collect. There are optional items on most levels, which can be much more difficult to figure out. If $40 for 10-15 hours doesn't make sense for you, no matter how polished and enjoyable, then definitely skip.
For me, it's totally worth the asking price. The game is gooooood. I love the artstyle, the progression, the puzzles--in fact, just about everything. There's enough variety and difficulty to make it a stellar title.
Also keep in mind that Nintendo rarely discounts their 1st party titles.