I'm not in a seaside location, but it's a popular tourist destination so I think a lot of the issues are the same.
One enormous pro is living somewhere that people travel to from all over the place, and being in a beautiful part of the world.
Cons include:
Inflated prices - housing is extremely expensive, lots ofAirBnBs (a friend has enormous problems with this; we fortunately don't).
In peak season: lots of people around who have no local reputation to uphold. They're far away from everyone they know and they don't care about chucking rubbish on the street, drinking too much, yelling and screaming late at night [obviously not everyone does this, I mean I don't behave like that when on holiday, but enough people do it that it's really noticeable].
Limited range of shops in some places where every second shop caters to tourists, so it can be hard to find things like a decent sit-down meal, or a quality butcher (for example; I'm veggie anyway). Lots of shops flogging tat.
Crowds/traffic/general overcrowding in peak season - enough to make me not want to go out at times because it's like tackling Oxford Street on Christmas Eve.
That said, none of those things would ever make me leave. Again, a major pro is living somewhere that I really love, and that I'm very proud to call home.