First off, I'd like to start out by saying that after I originally wasted nearly 26 bucks on minecraft (DO NOT BUY THAT GAME), I bought this game for just under 20 (should have bought when half off) and I got to say that "awesome" is the grandest of all understatement on a way to describe this game. This game doesn't come without its early game problems though, which i have serveral ideas.
1. You can't build road vehicles (disregard, it has been pointed out to me that artificial mass gives gravity to road vehicles)
Though you have wheels and suspension, you can't really build a small vehicles because they end up floating away, not that you need small road vehicles considering the concept of the game, but the wheels should be pulled down by gravity like the player is, otherwise, like i said before, it'll float away, i'm not sure why wheels exist in this game as of now, but adding gravity affect to wheels, and steering assemblies wouldn't hurt, it would really be as much usefull as much as it would be novelty, unless you have a REALLY large ship, which is what i'm working on, there will be a core of the ship because you'll need a vehicle to get to and from really fast.
2. Server lag.
I feel that the multiplayer servers and the way everything is handled when sharing maps could be done more efficiently, so much lag and is very network intensive, i work with networking and computers and the way everything network in this game is being handled, is not doing so very efficiently, i'd have people join my maps, complain about the extreme lag, and leave, like clockwork.
3. Some of the cubes are limited.
For example, on large ships you can only place large cubes, and for small ships, you can only place small cubes. When you are configuring your toolbar, there is a category for large cubes, and a category for small cubes, they aren't really large or small, the size of your cube is completely dependent on the type of ship you're building, so the "small cube" "large cube" categories are somewhat confusing, i think it could have been thought out a little better. Another note on the cubes are the passage way cubes, i forget exactly what they're called, but there are only strait peices, no T or L or + peices, so you kind of have to figure a sollution to make that cube work.
There are a few little things that bug me, but not enough to state them here, and yes, i am aware it is still an early access game, the 3 ones that i posted above were problems to me that i felt needed to be pointed out, overall, the game is super awesome and i would recommend this game 3 times over plus another time, definitely the best $20 i've ever spent thus far. Another thing i'd like to note is that it's also not as processor intensive i though it would be, as of now (12-11-2014), i have a pentium G630 on an asus p8h77-v and 3.5gigs of ram (32 bit OS) and a geforce 9800gt. The graphics card does become quite the convection oven though during gameplay it goes up to around 210 - 220 farhenheit, and that fan gets LOUD, if i didn't have the cooling i did, it would probably already be dead, it's minorly concerning, i have a second 9800gt that i might put into an sli but with only a 430psu, it would concern me.