I'm assuming you are talking about Disney Premier Rewards which offers 2% Disney Rewards on Disney purchases, food & beverage, groceries, and gas. Depending on where you sign up for the card, they offer
different statement credits. If you sign up in the parks, they advertise $100. I've seen some online (maybe Disney Shopping?) for $200. I got a
$250 statement credit by signing up via the link on the
Disney Cruise Line website. It's a $49 annual fee, and it is not waived the first year. That being said, I earned $60 in Rewards in my first month of use, so for 2018 the card "paid for itself".
My father has been a cardholder since 2012. I have been a cardholder since 2018. I have never had any issues with not getting the redemption cards... you just need to remember to order the redemption card about
3 weeks in advance of your Disney vacation. If you don't, you can still get your redemption card on property. I have gotten a redemption card in-person from Guest Services on the Esplanade at
Disneyland.
As for if it's worth it, it really depends on how you use it, and how much you spend on Disney travel and merchandise. My Disney Premier Rewards is not my only rewards card. I also have the Chase Sapphire Preferred which I consider my "travel" card, and a Bank of America cashback card, and I feel like these work pretty well together. My general rule-of-thumb to maximize rewards is that for gas and groceries, I use Disney Premier (2%), dining and travel on Chase Sapphire (2%). And then for bills and merchandise, I use whichever card I'm hoping to get more Rewards for at that time (right now I'm using Disney because I have a cruise coming up). If it's Disney travel (hotels, cruise, tickets), I book using Disney Premier - but note that Disney Premier does not give you 2% on travel that is not Disney-specific. So in addition to Disney Premier, I would suggest having another travel card that you can use for flights, car rentals, Ubers, non-Disney hotels, etc.