Pros:
This place is astoundingly fun and beautiful. I am fortunate enough to live 20 minutes from the course, so I play here 4-6 times a week. I am a recent die-hard fan of the sport and I have been playing since January 2010.
As many people have already said, this course is beautiful. It has holes packed with trees, uphill/downhill, left and right curve, long and short, a few with water hazards. They have water fountains spread out every 5 holes or so. The course is located in a park so there are trails/roads that people are walking/biking/driving through... you might not like that, but it just makes the atmosphere that much more beautiful for me. It's a place for everyone to go and relax.They switch up the pin location frequently (A, B, and C). They provide scorecards with pencils on the communal bulletin board in the parking lot (you can also print them out here). This place is a blast.
I'd say the reason Tyler State Park is ranked Top 10 in the world for courses is because it's managed by volunteers, which means people are truly dedicated to the sport and to the beauty and architecture of the course. Joe Mela has done an incredible job with the place. The design is incredible. They set up some obstacles with fallen trees, they just built new tee platforms and benches, they have unique and accurately drawn out hole preview boards, they have poles at each hole so you can hang your bag on them. They have it all. It's hard to believe something so awesome could be free and so easily available.
Come to Tyler State Park... it's worth it, it's fun, it's difficult and it will blow your freaking mind.
Cons:
What could the cons possibly be... maybe the one thing I would say is that #13 has 3 mandos and that is a little frustrating... it's my least favorite of the holes, but I still love it and can't really be considered a con, which just goes to show how awesome this course really is.
Other Thoughts:
It's amazing how well maintained the place is. People are nice and everyone is there for the same reason... they want to have fun and experience the architecture and uniqueness of Tyler State Park. A bonus is that you sometimes run into professional players who have tips for you if you think to ask. Some friends and I ran into Glenn Patterson - who is a friend of Joe Mela's and has played on his team in some tournaments - and he gave us some tips on how to improve our drives without hesitation (he is a monster with his drives). He is a perfect example of the people involved and the people there. Amazing Disc Golf community. By the way, he is there all the time practicing on the 15th hole... you will most likely see him.