I'm in a long distance relationship right now, and I wouldn't recommend to get into one with someone not totally worth it, or without meeting in the flesh at least sometime and having some sort of long term plan. You can't really date "casually" long distance, it's an all or nothing sort of deal, and you have to be willing to make that commitment.
And yes, it is hard not having that person you want to spend all your time with hundreds or thousands of miles away. That being said our time together is that much more special because of it.
I really wouldn't recommend going into one without some sort of plan of who could move when, looking to the future should be done in every relationship but especially long distance ones. Firstly if you're just seeking out a new person you haven't met to date I would highly recommend looking near you first (just one more obstacle to avoid) but if it just so happens you fall for someone clear across the country, don't chop it up just becasue of the distance but at the same time see if it has an real chance of becoming a short distance relationship. For me, if it were not for both of us in school right now one of us would have moved to the other by now, or in the near future. That's temporary though and will only keep us apart for x amount of months. I mean if you both are stable in your living situation and neither wants to get up and leave everything behind, then there's an issue.
It does work for a lot of people, there are a good number of relationships that start online which more than a few are long distance I bet. Also there are people who go away for school or work, I know a lot of high school sweethearts break-up after a few months away but they're young and stupid to begin with :
: And there's a lot of people whose spouses or partners are in the military which takes them away for long periods of time and those work out quite a bit. My Brother's girlfriend is actually in the Airforce so he's in a long distance relationship too, and last I heard even after spending literally every day together being apart hasn't put a strain on it.
In summary, it sucks but some people are worth waiting for.