Hi Yen--
I wanted something with more hand positions than flat bars, but more upright than drop. They feel very different, and have taken a little getting used to, but I think I love them, very much.
It has also taken a little tweaking to get the position just right. I used an adjustable stem until I found the angle I liked, then ordered a permanent stem. I've found that it needs to be higher and closer than drop bars, but for riding around town (which is what I want to use this bike for), it is terrific.
I found that if I move the hoods/brifters in closer together, I can place my hands on them almost like I'm riding on the hoods on drops. On drop bars, I hardly ever go down into the drops, because I'm just not that flexible anymore, but with the mustache bars, I can put my hands comfortably on the outside, straight part, and it is just enough of a drop that it improves the aerodynamics when I need it (it's very windy where I live). The only thing I miss is the straight part of the drops, but I find that the way my hoods are positioned on the mustache bars, I am rapidly getting used to it.
This is turning out to be the best bike I think I've ever owned--it is both comfortable and nimble.