Very trainable, easy to motivate with food, eager to please, fairly intelligent...but often a bit lacking in common sense.
More active than people usually give them them credit for.
Completely manic as puppies and teenagers, but usually fairly easy going by the time they're 2.
They shed fur like you wouldn't believe and once they get wet, which can be fairly often as they tend to like water, they take about 3 years to dry off and stop smelling of wet dog, lol.
They're basically walking dustbins and will eat everything and anything if given the chance, that combined with the fact that people underestimate their exercise needs means that the vast majority of pet labs I ever see are overweight, they're not a slight built breed, but they should still have a waist like any other breed.
Working strain ones are usually smaller and busier, show strain ones tend to be...a bit less mentally agile 
They do have a tendency to being overfriendly, though in all honesty part of that is encouraged by owners IMO...so just to put it out there, a lab bouncing over to play with other dogs whether the other dog wants to or not isn't being friendly, it's being overbearing and rude as far as other dogs are concerned.
If you go looking for a breeder, you want to have a low hip score, elbow score and a DNA test for PRA.
They do make great pets, because they are easier than some breeds, not less work but they're just so eager to please you that they're very forgiving of training mistakes.