I just got married in Brooklyn, and used Angel's Bakery II in Sunset Park.
We got the tres leches cake and it was amazing.
I think it wouind up costing $1.67 per slice, with plenty left over (and most people had more than one slice). It was so good that the catering staff was begging me for a referral.
The only caveat is that you have to go when they have an english speaker there or be brave and speak spanish. Free delivery.
This was better wedding cake than I'd had at any other wedding.
If you want a fondant covered cake, this probably isn't your place, but it didn't look cheap, and the line for seconds was 10 deep at one point.
somebody reviewed it a couple years ago.