1. First and foremost, there are very few constant features to my personality, most things about me change daily. Sometimes I'll be a very happy, cheery, friendly and energetic person, and then switch directly into being disconnected and cheerless for no reason whatsoever. The things that don't change in my personality are things that are related to what I'm either incredibly passionate about or that affect me emotionally, which is typically my hobbies or those I care about.
2. I used to be incredibly unsocial, but due to life's circumstances I have been forced out of my shell. I still have my days where I stumble over words or fail to find any words at all and just stare at you and smile, but those days are far and few between now. If I can tell that you are a type of person that I am compatible with, it would probably only take a day or two for me to be comfortable with you.
3. Don't expect to be able to get close to me. I only let people I've known for years know who I am when I'm not caught up with trying my best to be a friendly person, so most likely it won't happen for you. Even people that I've known for many years who think that I'm their best friend would be surprised to know that I restrain myself heavily to keep from being too personal with them. As of right now, there are really only 2 people that I open myself completely to: My girlfriend and my best friend. Sister doesn't count because... you know, she's my sister. :p
4. A major flaw of mine is that I would rather spend days on end working on my personal projects than with people, even those that I care a lot about. It's not that I don't enjoy spending time with my friends, I'm just a guy who likes to keep his mind busy and idle conversation just doesn't do that for me. If we hang out, expect video games or discussions about computers, computer hardware, or computer software to be involved somehow.