I'm in a queue to talk to Sony about getting my money back as we speak.
Copy-pasta from my customer service post:
I purchased DC Universe Online as a digital download through Amazon. I'm blocked from installing the game, as the DC Universe Online launcher tells me that my Activation Code is invalid.
I'm also blocked from the mandatory subscription set-up, as the Sony Station Account page tells me that it was unable to process my debit payment, without giving me further details. The funds in the account attached to the debit card are more than adequate to secure a $15/month subscription once my thirty days of complementary game time have expired.
I have no way of evaluating whether the game is worth playing or not, but the barriers to entry encountered so far are enough to sour me on my purchase. I've paid $47.54 for a launcher that launches nothing but a broken pay site. As Amazon.com's terms of service stipulate that they do not offer refunds for software applications, I'm forced to ask you, Sony Online Entertainment, for a refund.
The customer service forums are wallpapered with posts similar to mine. Customers who downloaded through Steam and Direct-2-Drive are experiencing the same difficulties, so it's not just an amazon thing. The feedback I've heard from other players so far is that it's a pretty decent game, if you can get in, but as a product launch, this looks like a clusterfuck.
ETA: I've found the problem, and it was a data entry error on my own part. It's downloading now. I'll leave this post here as a record of my own short temper.