Expanding on my earier post - you would, if you had a ship, have to manage and fly the ship for long stretches of real-time, and despite being an MMO, the game world would march right along regardless, while you're in transit between worlds. It woudl help if you had fellow players on yrou ship with you, so if/when you log in, there's yoru fellow "guildies" right there with you. Pretty boring, unless you wish to be a raider and prey on unarmed transports for their loot.
Keep money in yoru account, though, or you'll find your ship locked down until you can pay for the unlocking fee.
Ground stuff would be wide open sandbox MMO, where depending on your chosen professio (or lack of one) you could get missions with teh Browncoats, the Alliance, or whichever mega-corp (Blue Sun) you wanted to. Oh, and criminal elements.
Or, you could eschew all of that and play frontiersman on some fringe world and try to durvive the day-by-day of living in a recently terraformed planet, with insufficient resources and barely enough to eat.
Bonus: Reavers would be freaking scary
Happiness is zero-gee with a sinus cold.