I'd say the -R media is a step above the quality of the +R media... I'm one of the few who hasn't had particularly great luck with Ritek/Ricoh discs. Not saying they're crap, just that they're not what I'd consider a top of the line disc.
Some people are reporting they're suddenly getting Taiyo Yuden discs in the -R packages (!!). Not sure what that means, if Maxell's getting out of the business or not, but at least they're subbing in high quality media. (I'd say TY and Maxell are the 2 best -R discs made)