I just finished, roughly, a 5 hour mulitplayer session with two friends and my bro[two humans, an ape, and a bird xD]. We had oodles of fun.
Note: Stay the hell off ice planets until you have thermal undies or something.. you freeze fast. I learned that the hard way and had to flee an ice planet I wanted to explore.
I definitely want this game more than anything(well, almost anything....still wanting the 3DS which should be arriving in the mail quite soon *is ever impatient!*, and of course, the WW HD edition Wii U..).
So progression is a lot less chaotic now following the weapon/armour rework. Still I don't want to play too much because of more character resets to come.
I would venture a guess of anywhere between a month to two months. Possibly three months. Though the Chucklefish devs don't intend to be on phase 1 for too long, I'm sure.
You get the Molten core, which allows you to craft the Metalworking Station, this unlocks the next tier of gear, but more importantly, lets you craft the item that unlocks the Beta galaxy (ie. the next set of levels)
I got passed the newest boss in a day of playing. It really doesn't take long to tech up in Starbound right now. Also, just face tank the UFO once your wearing the top armor for tier 1. He won't do much damage[try to avoid getting hit as much as possible, of course].
The new jellyfish boss is pretty cool, though the boss CLEARLY needs some work yet.