Would you say prop trading is the second choice for grads failing to get into I banks?
I would say that for almost all successful prop traders, prop trading was the first choice, and that for most people that thrive in a career at a bank, banking was the first choice.
They are two very different environments and what Black-Star said about prop trading being high risk high reward is very true. The styles of trading are very different too.
The vast majority of people that start prop trading simply don't get good enough at it and move on to other jobs. However the ones that make it can work the hours they want, wear whatever clothes they want to to work and can make a lot more money than someone their age at a bank. On the flip side their is no salary and you will often (but hopefully not too often) have days or even months where after a hard slog you go home poorer than you started. You also need to bear in mind what a small proportion become successful and think about how you are going to afford to live until you do so.
In a bank you will get a very good steady sallary but you will have to live by the rules, brown nose the right people, get bossed around, and basicaly sell your soul for as many hours a day as they can get out of you.
But don't think that prop trading is going to be less hard work. You can make it less hard work if you want but then you won't get good at it. To get good enough to have a career from it you will have to work at least as hard and be even more dedicated than you would at a bank for at least the first year or two and you must do this in a more relaxed environment where you will need to push yourself that extra yard because other people aren't doing it for you.
Make sure you do an internship with a bank to get a feel for what that's like and also try to do a couple of weeks work experience at a prop firm as well. They really are very different jobs for different people.
As far as the CV is concerned the bank will definately be more impressive but the prop firm is by no means the killer some people like to make out. I know many many people (Too many!) that have left prop firms and gone into banks/ hedgefunds/ other good jobs. so don't worry too much about that.
Hope this helps,
Aspire
Oh, and by the way - All prop firms are not equal, only join a decent one (Search any names on here to see what people have to say on them)