Does not seem great. The total is deducted from your available credit so I guess the only difference is the interest. Citi's lowest interest I could find on their cards is 15.49%. So I guess if you cannot get a 0% offer the 8ish rate is appealing. If needed to finance something at Amazon I would just take fhe Synchrony hard pull. The terms are far superior to this Citi offer.
While I'm sure some people will found value in this. I don't buy anything that expensive on Amazon, that I'd need to make monthly payments.
But when I do, I use my Gold card to earn points. And if needbe I just use Citi BT offer to pay it back @ cheaper % APR.