Samsung's phones are a bit more expensive at every tier than competing devices, but it does offer competitive trade-in values for older phones. Today, those values are effectively doubled for most phones. You can shave up to $600 off the price of a new Samsung device if you trade in your old phone.
The new doubled trade-in values are a bit odd because Samsung decided they should all be nice, round numbers. The original trade-in values were very precise numbers like $312 and $246. Here's the full list of phone values.
So, the advertised $600 maximum value isn't technically double what you could get previously. The iPhone X was worth $399, but the "doubled" value is only $600. Even the iPhone 8 Plus is a little shy of double at the $600 tier. Still, most of the values are generous. For example, $400 for a Galaxy S8? That's much more than you can get selling it.
These prices are only valid when you buy one of Samsung's newest flagship phones: the Galaxy S9, S9+, or Note 9. You'll only get the listed value for your trade-in if it's in good condition, too. Damage will drop the number dramatically. To take advantage of the deal, you have to buy your new phone by November 3rd and send your old phone in by the 24th.