Pros of doing law degree:
It is venerable
It is difficult, and people know this
It is about law, but this is, of course, only a plus if you like it
You can tell people that you are doing a law degree, as opposed to other, shall we say 'lesser', degrees
You get to spend lots of time in your university's law library
It's fun
Cons of doing a law degree:
You have to do work
You must read books
You have to take examinations
People expect your knowledge to be boundless, and not just limited to legal topics