I fired it up last night on PC. I did have a couple of crashes early on, but after a short while it seemed to be running fine. My first impression is that it's a really satisfying experience. In a lot of ways it's the fulfillment of a dream of space games that I've had since I was a little kid. Just the ability to be on a planet, then take off, orbit the planet, fly to another planet through space, and then land anywhere you want to and explore. In that sense it's what I thought Destiny was going to be like when I first heard it described. Unfortunately, space travel in Destiny ended up simply being a menu/loading screen. This is the real deal and it's just immensely fun and gratifying in that sense. The crafting aspect is a bit more prominent than I was expecting, and although I'm not usually into that kind of thing, I was able to pick up how to do it quickly.
I'm not sure if everyone's starting planet is like this, but on mine there's a radiation factor that is continually causing my shields to be damaged, so that has added some urgency to my actions and I can't just stand around for hours marveling at every single plant and animal. When I scan something off in the distance, I have to think about how long it will take to get there and back and if I'll be able to do it in the time that I have before I need to repair my shields and life support devices. It's not hugely stressful, but it is something that needs to be accounted for. Even with scanning, there's a good amount of exploration and looking around that needs to be done, so the flow of the game is something that you have to be patient about. Clambering through the landscape and carefully looking around reminds me of Fallout 3 in a good way, without the option to fast travel, so it's got a heightened emphasis on survival.
Basically I just got to the point where I repaired my ship and took off, and then orbited the planet for a while looking at it. I am excited about the game and I anticipate that my playing style will be taking it slow, probably only playing for a couple of nights each week. I think the game allows for that more laid-back approach, but I could also see people playing it for many hours each night and being way into that.
By the way, I'm avoiding spoilers so if anyone wants to talk about some important secrets or whatnot, please use the spoiler tag.