If you're staining a brand new deck, keep in mind that either solid color stain or paint is a permanent choice. You cannot change your mind in a couple of years and switch to a semi-transparent stain; it's extremely time-consuming to strip solid stain from a deck, and even more work to strip railings. Once you choose a solid stain, you're stuck with it--and the maintenance required to keep it looking good.
Unlike semi-transparent stain, which penetrates the wood and slowly fades or wears away, solid stain can chip and peel on a deck. This is even more likely if the deck gets a lot of foot traffic. This means that each time you apply another coat--every 3 to 5 years--you'll have to scrape loose stain first. The peeling will become more pronounced over time as you apply successive layers of solid stain.
Solid color stain is like thin paint; it's opaque. While it allows more of the texture of the wood to show through, it will cover all the subtlety of the natural wood color and grain. If you value a natural or rustic look, solid color stain may not be your best choice.
Most solid color stains require no primer. However, if you stain redwood or cedar with a light-colored solid stain, you risk tannin staining. Tannin is a natural substance in some woods, and it bleeds through water-based paint or stain, creating light brown streaks on the surface. To avoid this, you'll either need to prime the deck first with oil-based primer or use oil-based solid color stain.