I was looking forward to playing this, as a big Terraria fan, and ended up kind of let down. In practice it basically felt like a series of nine Terraria challenge maps with a break for mining the stuff you needed for the next tier of gear in between them. Since most of the actual content in the game is in the nine hand-crafted dungeons, there's also not all that much replay value, because the actually interesting and difficult areas will be the same every time, which is kind of a letdown for a sandbox game - you should probably just treat it as a platformer with somewhat pointless Terraria-esque mining segments between the levels.
As far as base-building goes, it gives you some interesting tools like different "brushes" for painting terrain, but there's ultimately neither much reason nor much capability to build anything interesting - you only really need a storage area for chests ("hypercubes") of unused items and all of five different workbenches, and that can fit in a tiny dirt hovel. Meanwhile, there's actually not many interesting building materials in the game, most of which aren't available until you're halfway through the game, really limiting options that aren't just a dirt hovel. The block size is also absolutely miniscule, which has some benefits when it comes to base-building because it allows for fine control of what things look like, but it also makes it more difficult to build simple things for people who don't need that fine control.
Probably the biggest thing that made me dislike the game, though, was that it had janky controls. What seems like fairly simple jumps can be frustratingly difficult, and often failing them is punished with instant death spikes. Some of the challenges are also set up terribly, like Cave Dive and the second part of the final boss, to the point where my friend and I were reduced to just swearing at the game incoherently for a while. (The final boss also basically didn't work in multiplayer at all, unfortunately, lagging my friend out completely - another major point off.) The tiny blocks are perhaps even worse in the platforming sense, because they make it hard to tell whether an area is mined-out enough that you can fit through it, or if there's a teeny-tiny block in the way of a jump, or what, since the mining beams, while appropriately fast, can miss single blocks very easily. Similarly, while there's a large variety of weapons, most of them are of very limited use except for the basic blaster and the homing missile, such that time spent crafting them is basically wasted. Or not, if you psychically know in advance that the next boss is one of the only ones actually vulnerable to the disruptor.
On the plus side, nuclear bombs are hilarious and destroy things in ways that seem physically impossible. Not that this is ever really useful to you, but they sure let you take out your frustration on the game world.
In the end, I can't recommend Asteria, not even to fans of Terraria challenge maps. Everyone else should definitely stay away, however.