Worth it if you liked the plot of the first game, but definitely not a good deal for the puzzles alone. They messed up by adding free movement which added nothing meaningful, instead of sticking with fixed perspectives/point-n-click like the original. Quite a few of the puzzles rely on you struggling to figure out how to interact, so they're tediously easy or unreasonably difficult with no relation to your intelligence either way. There's even a speedrun achievement (3 hours) which makes you uncomfortably aware of how much time you spend walking around, fiddling with knobbly bits, and watching unskippable animations instead of actually solving the puzzles you came for.

I liked the vibe of Machinika Museum (which I did get for free) enough to purchase Atlas for full price on launch, but it's probably safer to get your money's worth by waiting for a sale.