This is a fantastic place to watch a spring training game! I've been to a few other stadiums, but this is easily my favorite. The gameday staff is always extremely helpful and friendly (and they hand out lollipops when you go to watch warmups on the backfields), and if you come in early, you don't have to pay for parking.
Lawn seats are pretty cheap, although the prices have gone up a little bit over the past few years. The food and drink options are stupidly expensive ($4 for a water bottle in extreme Arizona heat), but you can bring in as much of your own food and water as you'd like.
The backfield set-up is great, with lots of options to catch major and minor leaguers practicing, as well as a lot of grass space to just hang out and play catch with friends and family.