Always enjoy Nats park. Ticket prices (the ones upstairs) are reasonable. I like that as a family we can bring outside food in given how expensive eating at a ballpark can be. Facility is still nice and parking, while expensive, is convenient. Walkways can get overly crowded at times. The outfield area is great with seating and restaurants.
We go to games often during the season, and this park is by far our favorite. Access by Metro makes it easier, but we also drive and park on occasion, and that is fine too...just plan for TRAFFIC! Food is fantastic everywhere you go, and there are TVs everywhere, so that you can get up and wander and still not miss anything.
A nice ballpark to watch a great team! The staff is extremely friendly and helpful. Get to the ballpark early especially if you would like to shop, interact with players, get great pictures, and avoid the chaos that will ensue once the masses arrive. As expected, the food and beverages are a bit expensive and choices are limited. If you're a big guy, pay extra for better seats or plan on standing on the rails.