Resin bases are a fantastic way to customise your army, make a particular character stand out, and just add visual interest. They also can save a lot of time, without scrimping on quality if you're in a rush, or achieve an effect that's impossible or impractical to replicate over an army if you have something specific in mind.
Byron has written a post about picking resin bases on the blog, which can be found here: How to choose and work with resin bases.