Pros
Potential pros would be, if Visa has a particular role you can't find elsewhere, that will get you to the next place in your career, the experience may be worth going through. My sense is there used to be effort made to make the corporate culture more stable and give employees a chance to contribute pro actively, while at the same time prudently manage risk. So, though not impressive when compared to other Silicon Valley companies, not bad when compared to your average american corporate culture (especially East Coast corporate banking culture). Also, if you're looking for a 9-5 type gig, you can make that work at Visa, but why live in Silicon Valley if you're going to do that?
Cons
Except for the reasons listed in the "Pros" section, I wouldn't advise working at Visa. As mentioned above, my sense is that there used to be some effort placed on managing a reasonably effective corporate culture, with prudent risk taking, which, in all fairness, is difficult to do when you have more than twice the market share of your next closest competitor (there is something to be said for prudently maintaining one's market dominance). That said, everyone in Silicon Valley that knows anything about the payments space, knows that PayPal shouldn't even exist . . . I'll let you think about that for a second.