Reaction is a good summer scent. I got a bottle as a result of my wife buying her dad the AS version (it came in a set, so she gave me the EDT). He smelled it on a scent strip around Christmas time and liked it, but he only likes aftershaves.
It smells like Acqua di Gio minus the "tangy zing". My wife hates the zing, so it works better for me. Very fruity/melon type.
I believe it's suitable for all occasions, not strong at all. Would be out of place in cold weather, though.