The games building mechanics are good so far considering it's pre-release, but there are a few things that would elevate it beyond.
1. A No-Snap feature, that could be toggled on or off. so walls, foundations wont automatically snap to the next closest structure.
2. Standard walls, fences, etc should be allowed to be placed at any angle from where it is snapped to. you essentially get 365 degree's of rotation from where the object is snapped to.
3. Custom building. Custom walls so you can make custom shaped rooms. Custom foundations, floors, roofs can be sized to whatever shape you want or (floors/roofs) auto fill to shape of house area.
4. Allow for closer connections between structures and other structures or objects. And, similar structures should be able to overlap to some degree.