Decking is the ideal way to transform a garden.
Due to its construction, it can cover many types of land and terrain. Unlike paving no real effort is required to make the ground level or flat. Most decking is done using Pine that is treated (tanalised)
Once installed the tanalin should protect the timber from rotting for several years, but after 12 - 18 months it will lose its yellow colouration and start to go grey.
I usually recommend an oil based stain is applied after 12 months of a colour of your choice. Unlike a paint the stain soaks in and therefore doesn't wear off leaving unsightly patches with no colour. It is easy to apply being almost like water and is something you can do yourself with no decorating ability for a low cost.
One caution, I always point out is that if you don,t treat a deck it will absorb more moisture which in turn increases the likelihood that it will become slippery when wet. Caution should always be taken when walking on wet decking.