Basically a very pretty (but content-lacking) DLC pack for the first game. – Alto's Odyssey Review

It’s gorgeous, it’s compelling, it’s fluid... but there’s so very little new on top of an already incredibly-simple original game. You’ll note I still rated it 3 stars, because yes, it’s still worth it. However, the minimal mechanical additions and lack of meaningful long-term progression means that after an hour or two, you’re mostly grinding for some basic achievements. There’s not even something as silly as, say, a collection of little bits of llama art for you to slowly unlock with coins once you’ve completed everything. Once you’ve tackled the fairly-simple challenges, there’s nothing else to see or do. Fair price for the experience? Almost certainly. Disappointing that it doesn’t try to be more than it is? Sadly also true.
Review by ColinHuth on Alto's Odyssey.