A sampler is a good way to try out different blocks to see if you like them or not, to work out difficult blocks or try new things. Such as sashing and boarders. Your quilt is just that, 'Your Quilt' so you can do what you like with it, for show or wall hanging or on a bed! I think they are a very good way of leaning or of teaching someone new to quilting as you do not get board with doing the same block all the time and if chosen carefully each block can teach you new skills.
Some sampler quilts are very skillfully done and not just for beginners, be sure to pick one to suit your skill level.
They are fun to do and have great charm IMHO!
Gal