Well, blocking generally does wonders for a knitted project. There are some really rare cases i won't block a piece i've knitted. Blocking makes the stitches even, patterns start "popping out", if you block after washing (not steam blocking), you are also washing the dirt from your yarn. Many garments will look shapeless and bulky, but after blocking to their correct size you'll get a perfectly wearable, drapey and well fitted piece of knitwear. There are certain fields of knitting where blocking is a "must", such as lace. As someone once mentioned, knitted lace looks like a cat's puke before you block. It's not worth knitting lace and not blocking it. Same goes to sweaters, IMHO. The same goes to colorwork/Fair Isle knitting. It usually looks bumpy and blocking gives the pattern it's best look.Here's
an excellent example by the forum's blocking guru, ArtLady1981/aka Dollyce how blocking is done and how it changes the way a garment looks.