I'm just not sure you want a bunch of 13 year olds reviewing your game just yet.
(2 hours played)
"Built a ship, attacked a station, died, no more money, 0/10 would not play again, wait for a sale"
Yes, I'm joking, but people are making their buying decisions like this now.
This is exactly what is going to happen if some of the game's mechanics aren't reviewed carefully before releasing it on Steam.
For instance, it would be a good idea to make a player always re-spawn with at least a core. It's also a good idea to check whether the AI isn't too vicious or spawn-happy (like 20 of them spawning in one sector) or whether the player understands what he should do (tutorial must be good enough).
Adding achievements could also be very helpful, something like "visit a planet" will ensure players understand that they can actually land on the planets for instance.
Finally, it's going to be of crucial importance that all server owners understand what is going to come with steam release. There will very likely be a massive wave of players incoming, server owners should make sure they have enough staff and power to handle those players and not forget to put caps on their player-count if they can't take it, to spread the load. A lot of players are instantly going to jump online (as we saw with the "Yogsstorm"), so making a good impression there will be very beneficial to the game. I assume this is a reason why servers got enhanced so much all the time regarding performance :D
It's also a good idea to elaborately point people to the website on the store page, people can use the live-chat here for quick questions and such and get involved more easily with the community like that. You don't want them to mass up at the steam forums while putting your focus on this site or social media, Starbound made that mistake and now look at their store page/steam-forums.