How do you feel about online relationships?

I am not in an online relationship, but I have talked to people off the internet that I’ve been in contact with for almost 4 years now. I am somewhat hesitant to start a long distant relationship with this guy who lives in another state.. but I still don’t know how I feel about this kind of relationship. Long distance, trust issues, a mental-only type of bond, ..These are all negative things that I always turn to when analyzing it. A positive part of all this is that we talk from time to time and that we’re able to accept each other mentally and emotionally. We have an understanding.. and we do talk of a future.
A major issue with this is that we’re both busy people, and we’re just living our own life. We both know that there’s a lot we need to accomplish on our own (education, financially) before trying to build up a serious relationship.
Now what I want to know is, Is it a waste of time for me to think so much about this kind of relationship? What do you think makes a successful long distant relationship? Does this look like a lost cause? How do you stay committed to something like this? Is talk cheap? I don’t know what to do.. I’m on mood swings here, sometimes I’m sweet and dream to be with the guy, then sometimes, I feel like giving up on him.. Help?