To get a bit back on track - I've found MegaReader to be an acceptable replacement for Stanza. While it's not yet as customizable and versatile as Stanza is, it already features OPDS catalogue integration which "feels" faster (with Calibre's server in the backend) than Stanza's.
The reading interface is plain and nice, IMHO, and works well. No fluffy book-like stuff (as in iBooks) but just text like in Stanza. The famous "swipe-to-control-brightness" is not implemented either, though.
The only other slight downside is that it's not free (as in beer, this time :-) ).