Are we talking the 1x2x1 dark tan that showed up in Ninjago (and will have a much bigger place in light/dark stone in the upcoming LotR) sets?
I think the real thing to look at is if we mean bricks or blocks, because even though people hate to use that term, that's what LEGO parts really are. I think they're absolutely lovely, and have been buying the heck out of Ninjago to get some of them in tan. But then again, I'm more of a town/castle builder, so I can see a whole lot of purpose to them.
That's not to say I think they're going to replace the regular 1x2x1 brick... they serve a different function. They're more an accent piece, like that lovely modular above. And like any new part, it can be overused easily and ruin any effect. But they're not much different from any other new part, like the various tiles, modified bricks, or stickers.
My only beef with these is that they tend to make a very regular pattern when you put them there, and don't mesh well with other bricks, unless you do it exactly right. If anything, they're harder to use than normal patterns or old methods of staggering and creating brick patterns.
You know, if I see links to Brickshelf, more often than not, the first thing I click is the "Back" button.