The phase-I upgrade of the Compact Muon Solenoid (CMS) pixel detector has been designed to maintain the tracking performance at instantaneous luminosities of 2 x 10^34 cm-2 s-1. Both barrel and endcap disk system now feature one extra layer (4 barrel layers and 3 endcap disks), and a digital readout that provides a large enough bandwidth to read out its 124M pixel channels (87.7% more pixels compared to the previous system). The backend control and readout systems have been upgraded accordingly from VME(Versa Module Europa)-based to micro-TCA(Telecommunications Computing Architecture)-based ones. The detector is now also fitted with a bi-phase CO2 cooling system that reduces the material budget in the tracking region. The detector has been installed inside the CMS tracker at the start of 2017 and is now taking data.
In this presentation we discuss experiences in the commissioning and operation of the CMS phase-I pixel detector. We also present the first results from the CMS phase-I pixel detector in this year's LHC proton-proton collision data. The new pixel detector outperforms the previous one in terms of hit resolution, track resolution, and vertex resolution.