My wife got my 1990 550 for 400 bucks with case shipped, and I won an auction for a 2018 genisis for 600 shipped.
The prices are great values if your are patient and look for them.
Over/under rated depends on who you ask.
My opinion for example.
I hate Les Paul's, I hate strats and I hate teles.
Most people Say they are the best guitars ever.
Les Paul's are uncomfortable for me, I've never heard a strat that didn't remind me of a whiny child, and teles are ugly.
That's just got opinions go. They are only right to the person who has the opinion of is of a like mind set.
I absolutely love my 550s. I currently have 4 of them.
Yes, they were meant for a specific kind of sound, but so is everything else.
The fact you can choose your own pickups if you want, on a y guitar, means you choose your own sound too.
I will say that Alot of what the rg line turned into during the 2000s was more directed at metal and thrash, sure. But they still had enough verity to appeal to almost everyone at least slightly.