usually not hard to get in. As stated weekend days and stuff can be tougher.
Some advice for first-timers -
depending on the day the lines can be very long waiting to get on the busses to go. If you're planning on taking anyone who is older and isn't going to be able to stand around for a long time, you may want to call to see if you can arrange to park in the parking lot at the facility. My father has a disability so we just drive there and skip the wait. But you have to make sure you call ahead to get on that list.
There is very little shade there so if you're going on a sunny/warm day make sure you bring plenty of sun block, possibly an umbrella for shade if you can find a place to station yourself that isn't obstructing anyone's views.
It's also a good idea to bring some folding chairs if you have something compact enough to take on the bus ride. They also sell some folding chairs there.
They have food and beverages and other things there are surprisingly reasonable prices, nothing seems to be gauged too badly. If you do end up going on a particularly warm day do yourself a favor and either bring water, or buy some bottles of water there early, a couple per person, they've run out before on hot days.
Overall I've been to training camp practices about half a dozen times, they are always a good time and really ramp up the excitement for the season. They are what they are though - a practice, so if you bring kids anticipate that they are going to get bored and realize you may have to jump on a bus early.