Your characters from Destiny's beta won't carry over to the full version. Bungie explained why they decided to wipe everyone's Guardians.
"Since the Beta, we’ve continued to tune and adjust the game," said designer Tyson Green in the Bungie Weekly Update. "The way you earn experience has been adjusted up and down a bunch of times. Items have been added and removed. New features toggled."
"Although there’s no single monumental change, the sum of the tweaks leaves characters from the Beta Build in strange shape that would be confusing at best, broken at worst."
Also, the test didn't allow players to try out every specialization path for the character classes. You may find that you want to take your launch character in a different direction than you pursued in the beta. Or you'll pick a new class entirely.
Destiny's beta allowed players to advance up to level 8. It only takes a few hours to get there. Still, I'm sure that some players sank some serious time into their characters. The special Iron Banner PvP events allowed players to earn exclusive rewards. It's easy to get attached to strong stats, too.
Still, Bungie says that your beta characters will be quickly dwarfed by your final version toons. They illustrated this point with a screenshot of senior artist Matt Bennier's Warlock from the full version. He's decked out in some very impressive gear:
"Grab your Destiny Companion. Look at your Guardian. Now look at Matt’s. Now back to your Guardian. Now back to his. Despite your brave service and fantastic exploits in the Beta, it was only your first step into the wider world of Destiny. A small (yet record breaking) percentage of you barely even ventured to the Moon. There is so much left to do – so much left to earn and master."
"Right now, you’re lamenting the loss of your starter gear, those pearls of mayhem of destruction that you carved from the wastes of Old Russia. Look beyond that horizon. We have exotic arms and armaments secreted away – adventures you can barely imagine right now."
The only thing that players will be able to take with them to the full version is a nameplate for their character. Everyone who traveled to the Moon during the Moon got an exclusive nameplate. A separate nameplate will be given out to everyone who played the test at all.
Destiny players will eventually be able to explore other planets in the solar system like Mars and Venus. When they hit higher levels, they can undertake six-player missions called raids. Raids are difficult encounters with unique bosses. Bungie said that they will "demand of you things you’ve never even really been asked to do in a shooter before."
Bungie will launch Destiny worldwide on September 9th for PS3, PS4, Xbox One and Xbox 360.