What is it? Nothing but a sign! But just like the Hollywood sign in LA, the Welcome to Las Vegas sign is a historical landmark that everyone should see at least once! Most people will wait in line, but standing on either side of the line to get a picture could be just as good!
If you insist on standing in line during the day, bring a had, umbrella, and lots of sunblock, or wear clothing that covers your skin because that sun is BRUTAL! There's a person who works to control the line, so it doesn't get crazy. It's probably not something I'd do every single time, but I also wouldn't mind getting a picture here again one day!