Last night we had the kick-off of the new Mass Effect campaign using a hacked version of the Cortex+ rules. PC creation was done as a group (ala Fate), with the GM guiding everyone through each step en masse. So for example we would all pick our races, then be informed of the impact it has on your PC, and then pick a background, be informed of the impact it would have on your PC, etc. By the time it was all done we had one gun-berzerker, two snipers, one engineer (me), one medic, one Vanguard (whatever you want to call them--I call him a Jedi), and one diplomat.
Now one thing I saw during this process was a couple of players getting frustrated with the fact that they didn't know what would happen as a consequence of picking a certain option. For example, say you decide your PC has the "Colonist" background. What skills would you think you would get? Tech? Survival? Medicine? You don't know. Some players started asking the GM questions like "which option would boost my combat abilities?" etc. At least one wanted a "do over" on his decision.
Now I don't mind having a little less control of PC creation; I kind of enjoy playing someone out of my comfort zone who may not be totally optimized for whatever role he is supposed to have (I even like Traveller, where you have almost no control whatsoever). I saw my really undeveloped concept take shape as the process went on. But I could tell that a few people found the experience a little different from what we are used to.
What was really good was the establishment of the relationships between the PC's, which seemed to help gel the team together. In the meantime, the GM has asked me to help put some minis together, so that will give me some things to work on.