To ensure a healthy gravel staircase installation, you need to understand how pea gravel stairs break down over time. So let's take a look at what can and does go wrong. If by “major” you mean “relatively minor,” there are three major problems. The pea gravel is kicked away. The wood you use to hold the gravel will rot by the time your grandchildren are old enough to replace it. And the stairs will almost certainly sink a little over time. Regarding the first concern, you can top it with pea gravel or cover it with cement or epoxy. Pea gravel is rounded and unlike other types of stone used in landscaping, it can become slippery with moss and mold, but proper installation will reduce this risk. When it comes to wood, the residential use of chromated copper arsenate in treated wood was only reduced in 2004, so no one knows how long alternatives like alkaline cupric cupric will last. If you're concerned, you can spend a little more money to buy plastic or composite wood alternatives.
You can't imagine the sinking feeling you'll get when you see your pea gravel stairs a few months later. There are several factors that cause settling over time, including gravel loss from traffic, soil settling, and erosion from rain and sprinklers. Erosion can be exacerbated by the activity of burrowing animals such as gophers and ant colonies.