I tried the base building, and found the inventory system made the whole thing really painful - like they used it as a reason to expand the crafting tree.
You can build a teleport to get back to your base, but it needs power, so you also need to build batteries, wiring and solar panels to keep them charged. You can build extra storage units, but they also need to be actively powered, and somehow store less in ~10 cubic metres than you can fit in your suit pockets. And introduce another inventory screen that behaves differently to all the others.
You can build cool underwater bases, but I ran out of materials for an airlock and water filling through the floor hatch behaves a bit oddly.
You can also build hangars for ground vehicles, or even submersibles, but I ran out of patience before trying one. It wasn't at all clear whether you also have to build or buy the vehicle separately, or how much use you'd get out of it.