None, backyard play, but have looked at other fields
Since moving to Oregon, my wife and I have been to several local paintball shops. By far, Bob's shop has been friendly, outgoing and very helpful in choosing paintball equipment, add ons, etc. We have played on OPB's field several times, woods play, scenario, and recently speed ball. The speed ball field is smaller, but still fun and well laid out. It is laid out on sloping terrain, so nothing is flat.
The main field is wooded and on about five acres in the country, with several bunkers, buildings and forts. They move the teams around at each game (15 minutes per game with 7 minute rest breaks which keeps the games moving. First 5 minutes, you can regenerate to keep playing and have fun. Which is extremely important to the staff.)
Speaking of the staff, they are very excited about the game whether at field or in the shop. Safety is number one followed closely by fun. The is little tolerance for unsafe behavior or rule breaking. The staff is very personable, Bob,as well as the other staff, is often seen wondering around to make sure everyone is having a good time. When my wife's marker went down, he offered to let her use a rental free of charge. He also will help repair markers at the field even if they are not rentals.
Pricing is very reasonable, esp as a parent with a fixed budget. Field fee with own equipment $15 (rental $25). This includes one CO2 fill, complimentary pop and snack. Paint runs about $65-80/ case depending on brand, but he also allows you to buy paint at his shop in Gresham at shop prices to bring to the field.
To sum it up, I give Oregon Paintball a 10 based on everything I have said. It's worth the drive. Hats off to Bob and his team! (BTW, our two year old loves to go and visit Bob and see PAINTBALL!!) Hope to see you there and have fun!!