Everyone described it just right.
I prefer OWS because I once had a head on collision with someone who was passing and not looking where they were going. If the lanes are wide, it's just fine. If the lanes are narrow, it can be a little tight.
Give me a lake anytime. I'll most likely swim farther than I'm supposed to, but no head on collisions, or slow people (who fibbed about their swim time) to slow me down.

It just depends on your preferences. Some people LOVE pool swims, some people hate them. You won't know until you give it a try...
Have fun if you do the tri on Monday, and tell us all about it.