My gf and I did the long-distance thing for about a year - she was in Michigan, I was/am in Seattle. We met at a wedding here in Seattle about 2 years ago and really clicked, but we were both afraid to jump into a relationship right away, largely due to the distance but also because we'd just gotten out of really awful long-term relationships. When we decided to go for it, we went into it knowing that one of us would eventually have to move. She moved here last July and it's been great, damn-near perfect really. But the whole time we were long-distance, we made time for us - talked on the phone every night, texted all throughout the day, and visited as often as we could. The longest we went without seeing each other was 6 weeks, but on average it was every 3-4 weeks; it wasn't cheap, but it was totally fucking worth it.
As for advice, I'll echo what other have said: You both need to give it your all, so talk every day, see each other as often as you can, and know that one of you will eventually need to move if there's a future for you two. But before you guys make that jump, you should have the serious, future-oriented discussions - kids, marriage, etc. Doesn't make sense to uproot one's life if there's an expiration date on the relationship. Also, being only 4 hours away from each other, you should be able to see each other every weekend; definitely try to make that happen.
Best of luck. Others may have had bad experiences, but it can work if you both put the effort into it. If nothing else, you'll at least be able to say you gave it a shot when you had the chance.