From what I have seen in your website and from having spoken to few others, I realize that its likely I might get through the first filtering process, since I have a good school name as a backup, and my academic record and extra curricular activities are not bad.
That brings me to my question. It might sound really strange, but your views would certainly help me out. I have long hair, and wear a ponytail all the time. If I am lucky enough to be invited for an interview, I don't know if it would be appropriate for me to go with my ponytail. If I manage to do well, and if I am given an offer, then getting rid of the hair is no issue.
Would my long hair come in the way of my assessment at the interview?
Short Answer: Yes, the pony tail is a problem.
Long Answer: The underlying question the interviewer asks him/herself is, "Do I want to put this person in front of my client?"
For the top tier firm, the standard rule of thumb in terms of appearance is to dress and appear one level more formal than the client. If they wear blazers, you wear blazers and a tie. If they wear t-shirts, you wear a button down shirt, etc...
The pony tail kind of ruins the conservative image most firms want to have. I think the pony tail will cause many clients, and therefore interviewers, to be immediately biased against you.
I personally would not put a guy with a pony tail in front of a client. You start off the relationship in the hole which makes the whole thing much harder.
If I were in a case interview, I would probably be skeptical at first. But if the pony tail guy really nailed the case... and I mean really nailed it (got it right), I would probably pass him but tell him there's no way he'll get past the final round with the pony tail and suggest that cutting it off would improve his chances.
First impressions do matter... and the pony tail image is not the image a BCG, Bain, or McKinsey want to convey.