In my experience, LEX is a reasonably comfortable but extremely slow way to travel. What should be a three-hour trip can stretch to four or five due to the numerous stops and transfers you may have to make. (On the upside, there are a lot of stops to choose from.) Tickets are usually pretty expensive, and there is no wi-fi on board, so make sure your wallet and your iPod are properly equipped.
Most of the drivers I've had have been friendly and punctual. Some like to speed, and I have heard of accidents, but for the most part, you should be fine.
I like that you can simply walk on without a reservation and pay your fare in cash. This can be very expensive, but it's a godsend when you're in a rush and have no other transit option available.