Tough call really. I was going to trade my note8 in but didn't for the same reasons.
Read their fine print, if your phone doesnt meet their standards, then they'll only credit you $25 for it and not return it. That's not worth the gamble for me. I could sell it elsewhere for much more than that, if not the $400 they're offering but might not give me for it.
I've seen some complaints in the past, but nowhere near the claim that their trade in process is a total rip off. I'm sure they have thousands of people sending in phones for trade ins, and those few that has bad experience are a tiny percentage to worry about it too much. I personally traded in a TV for a new Samsung TV, and it worked fine. I'm trading in my Galaxy S9+.
and if you decide to return the Note 9, they will keep your trade phone AND they will not return the "trade in value" either. So they effectively force you to keep your purchase. They are treating the trade-in discount like a coupon code, not a valuable item used to offset their ridiculous retail pricing.
Ridiculous pricing? You don't have to buy something you can't afford man. Samsung is not cheap, but it's still a decent value compared to some other top brands out there.
These phones come with warranty, right? Any reason not to exchange your "lemon"?