Well, I like. Having little personal control over the start is handy, as adventurers can spend longer selling their loot than looting it... But it raises issues as the mystery will largely die as soon as you meet someone familiar with your expedition who isn't being deliberately obfuscating on the issue. This could me mollified by taking you someplace alien, or being someone alien, showing up in terran space as the only amorphous blob monsters with a fixation on headdresses and hovershoes that anyone has every heard of lets you have civilisation without knowing your past... And no doubt there are plenty of backwater locales that will give you a chance to much about before finding any civilisation at all if that is a preference.
I have a fondness for the freedom of having my own character, but it raises many issues, such as players not responding in time for an update, people being stuck of a waiting list, people running off on their own tangents with no regard for the rest of the group... perhaps a hybrid system, people nominate a character they will control, but one character can have many controllers, or people can only submit actions to one character per update, meh, those are exploitable and difficult to police... If a player doesn't post within 24 hours then their character falls to mob rule? Events can happen that cause a character to change players? So, say, if you jump out the airlock, then you die and a new character rocks up with a new player, but if you see your best friend torn apart by the bugblatter beast of Traal then your mind breaks and you get a new one... Sanity checks to keep hold of your player could help with player turnover at least...