Seems to work fine. I initially thought I had a problem with this or cable (would only go up to 1920x1080), but it turns out it's either my Dell docking station and/or Acer monitor that's at fault..
My dock has 2x DP outputs and 1x HDMI output, and I've got 1x DP monitor and 2x HDMI monitors - so I need one of the HDMI monitors to have this adapter. Using the adapter with my BenQ monitor is fine - but whether I use it on the BenQ or Acer, the Acer is always stuck at 1920x1080. If I plug in only my DP screen + the Acer, the Acer shows 2560x1440 just fine ... so no matter what, if I connect 3, the Acer isn't displaying the right resolution..