Pros: You get to meet a lot of really laid-back, cool people who give you money and treat you like a minor celebrity. I had one woman stop and pick me up, she started going on about how she wanted to backpack europe, and asked me for stories. So I told her a few, some true, some not, and every time I told her a story, she just acted as though I were a legend. Great for the ego.
Another guy took me to the lake-shore in my home state, showed me all the best spots to relax, gave me funions and 20$.
Another time a guy drove me all the way from Chicago to the front door of my parents house and supplied me with at least 50$ worth of snacks.
Cons: Standing on the roadside for 8 or 9 hours listening to the same playlist over and over again. Have people swerve at you , flip you off, and give you thumbs up. One can only play "pebbles" for so many hours.
Also, getting hurt and sick can be really rough if you are not in a good spot for resting. I fucked up my leg one time. It was late fall and every time I shivered in the night a blast of pain shot all the way to my hip. The next morning I was trying to get out of town and had to hop on one leg for like 3 miles, stopping every few hops to rest my leg until a nurse saw me, and picked me up and gave me some pills and a ride. She was late to work and everything. It makes a good story to tell to friends around fires, but I was close to crying at the time.
In summary: Hitching is amazing, and I believe addicting. You meet so many people, get so many stories to tell, and wind up in the most unexpected places. It's definitely a good way to travel.