It made transition between windows smoother, so much that when I switched back to Dalvik I couldn't stand it (the short waits between tapping on something and reaction, like tapping on home or recent buttons). It's not faster like a faster CPU, but it does seem to suffer less from interface stutters. It's more of a subtle feel, similar to when you run iOS6 on an good specs iPad where everything feel smooth. I feel ART made the entire argument of iOS(7) being smoother invalid as this point.
Since we already have fast hardwares, it's hard to tell the difference since it's differentiate by fractions of a second. Some apps should load faster too naturally due the ART compiling the complete program to machine code.