Well to state the obvious....shelties are not labs. So if you like the happy go lucky energy of a lab a sheltie may not be for you. I only say this because shelties are for me and labs are not.

Shelties can be great dogs. I will list their bad points for you though as that's what you'll need to know to decide if you can live with it or work with it.

Shelties shed and need more brushing than labs.
They can be quite the barkers, and can be quite reactive.
A lot are reserved and prefer to wait to get to know a person. They don't run right up to whoever looking for pets.
They are a herding dog and can tend to be nippy at things running quickly past them, whether that be kids, cats or other dogs.

If you have any other specific questions just ask