The only issue that we've seen with this card is in the late hours at night and early hours in the morning (7am and earlier) Amex server seems to be down a lot. This means that you can't transfer funds from your Reserve account to your Balance. If you have all of your money in your balance then this will not affect you because you can still make purchases with the card.
American Express Serve Cons - The only thing I view as a con about the Serve card is that American Express isn't widely accepted as Mastercard or Visa. This means you may have to have a second prepaid debit card with the Mastercard/Visa logo or pay with cash. Paying with cash means you have to go to the ATM and be charged a $5 fee on top of whatever your purchase cost, costing you more money.
There are many negative reviews online from Serve cardholders about their accounts being suspended and being locked out of their account. One cardholder noticed that when users make large direct deposits over $1,000, it seems to trigger a fraud feature within the Serve card where users are locked out almost immediately.