This review is for the Signature Series with a "1" in the model no. I believe it's D10US. It's important to distinguish this from the other Yoga 900's as this model has higher performance RAM-memory 1866 Mhz vs 1600 Mhz, PCIE (not SATA) Samsung SSD, and Intel Iris graphics. I bought several of these during the Pre-Black Friday sale. Reluctant to purchase them since there were only a handful of reviews I took the chance after I went into Windows 10 Device Manager and looked at the hardware ID's and looked up the specs while in the store. What a deal!! I waited to write a review until I had some experience with putting it through some thorough testing and benchmarking. Unlike some other earlier reviews I have not had any issues cited in other reviews. Recommendations to avoid any potential issues previously cited. 1. Perform all Windows 10 updates before doing anything else. 2. Disable all Windows 10 Privacy settings and Apps running in the background. (Windows calls home more than you can imagine and lets others call your PC if you don't disable the Privacy Settings) 3. Download the Intel CPU Diagnostic tool and perform all driver updates. I prefer to go to the part manufacturer's website to update drivers and or firmware. Intel is highly recommended vs. Lenovo for CPU and Graphic updates. 4. Change your "Power" settings in your Control Panel or Lenovo app to meet your needs when you are on battery power or direct AC power. I changed he settings to "High Performance" on all settings when on AC and balanced performance when running on battery. THIS MAKES A BIG DIFFERENCE ON performance, heat, fan noise, etc. Though I never had any obtrusive fan noise even when using Intel CPU Diagnostic Stress test or streaming Hi-Def video with 20 web tabs open. I downloaded Hardware Monitor a very useful program to monitor temps, cpu and gpu utilization, and many other useful system monitoring data when testing and or diagnosing performance problems that may be caused by hardware issues. The Intel I-7 CPU and GPU were stressed in testing and passed with flying colors while the system remained at very acceptable temperatures. Koodos to Lenovo for design and engineering. 5. Browser- Set your default browser to Chrome. Chrome offers better performance than Microsoft Edge, Firefox, etc. 6. 4K DISPLAY IT'S AWESOME BUT - takes a lot of juice in the form of power and hardware-graphics processor, power integrated with the CPU. Recommend using the Intel Display app to change to a lower resolution when on battery power. The 4K video is awesome when watching 4K content or doing high resolution video or graphics work. On a 13.3" screen 720P is still going to look awesome while keeping your system cool and really extending your battery life. The audio sounds impressive for an Ultrabook however make sure to use and adjust the "Dolby" audio settings to your listening preference. Though I give this 5 stars there are some things Lenovo could do to make it a better product. Improve and or change the following; Backlit keyboard is nice but the right side layout needs improvement, touchpad feels great but it took a lot of adjustment to decrease the sensitivity, USB_C is nice forward looking tech but I would have preferred an HDMI or mini-displayport out, and Lenovo PLEASE improve your canned responses with more helpful, resourceful, and links to useful tools.