Pros of basic income:

1. On steem it can give you the ability to gain more Steem Power without getting economically involved, so that's good if you don't want/are not able to buy STEEM$ with your money.
2. Outside: with a guaranteed income you may have less worries since you can work less and you aren't totally without an income if you lose your job.

Cons:

1. I think I'm not expert enough to see why basic income can have cons on steem it,.
2. In real life well... that income must come from somewhere, that somewhere being someone else that may disagree with having to "fund" someone for basically doing nothing (that's actually a simplification maybe).