I have a Tiagra compact crank that beat the pants off of a Truvativ crank. Not that that's difficult, either...

But, functionally speaking, it was as nice as the 105 compact I had on another bike, and also as nice as the R700 on a third bike.

Anyway, more relevant to the original question -- I just swapped my commuter from flat bars to drops with Tiagra. This bike already came with a Tiagra FD and RD and a Sugino crank (the Tiagra one I mentioned earlier is now on standby in case the Sugino bites the dust). The shifters work fine, and I'm satisfied with them. The 7800 shifters (on the third bike with the R700 and 6600 FD/RD), however, are tasty smooth. Worth the huge retail price? Nah, but they're easily worth the liquidation price I paid.