I wasn't anticipating that I would see much of an increase in performance going from 1.2Ghz to 1.4Ghz processor speed and faster networking, but I was wrong.
This Pi seems much, much faster than the previous P3 B models. I'm not sure if the improvements are from the new OS, The CPU or the Networking, but Chromium was painfully slow before, youtube was barely keeping up in a small window and opening more than one or two tabs would bog the entire system. Now I can view a youtube video full screen (1920x1080). Everything works quicker. It's a viable desktop machine at this point.
There are a few quirks:
1) My Keyboard and mouse go through a USB hub and then a USB KVM Switch. This would not work due to "USB Device nested too deep" error in Linux. Had to remove the hub and go straight to the KVM. So there must be some difference in the USB controller from the Pi 3 B.
2) Even though the P3 B+ supposedly uses less power, I occasionally see the low power "Lightening Bolt" warning when the CPU is really maxed. (Like trying to watch a video through VLC, epic fail). This is with any of my 2.5 amp Canakit Power supplies that NEVER gave me a warning on the Pi 3 B. **(see below)
3) You must use the new Raspbian Strech version of Raspbian. Raspbian Jesse would not boot.
I'm still giving it 5 stars because most folks won't have an issue and I am so impressed by the performance improvements.
** (edit) I discovered that my low power warning issue went away after removing the in-line microUSB On/Off switches that I normally use. I'm not sure why the non-B plus Raspberry Pi's had no issues with the switches. Nonetheless, the new P3 B+ gave no power warnings (even under heavy CPU loads) when I plugged the USB power sources directly into the Pi's microUSB port.
IMPORTANT NOTE: If you see a rainbow splash screen with a lightning bolt symbol, this indicates you are NOT using B+ compatible software. NOOBS 2.7.0 or later is required for operation of the B+. An exclusive kit from CanaKit that includes the fastest model of the Raspberry Pi family - the Raspberry Pi 3 Model B+ (B Plus)!The Raspberry Pi 3 Model B+ is the latest production Raspberry Pi 3 featuring a 64-bit quad core processor running at 1.4 Ghz. It incorporates built-in WiFi and Bluetooth connectivity with enhanced dual-band 2.4 GHz and 5 GHz WiFi, Bluetooth 4.2/BLE and faster Ethernet.To take full advantage of the improved power management on the Raspberry Pi 3 B+ and provide even support for even more powerful devices on the USB ports, a 2.5A adapter is recommended.The power supply included in this kit incorporates a noise filter to provide the highest stability and comes with a 5-foot cable. This power supply can power the Raspberry Pi 3 B+ and other USB accessories (such as most portable hard drives) without requiring an external powered USB hub.Kit Includes: Raspberry Pi 3 Model B+ (B Plus) with 1.4GHz 64-bit quad-core ARMv8 CPU (BCM2837B0) 1 GB LPDDR2 SDRAM CanaKit 2.5A Micro USB Power Supply with Noise Filter (UL Listed) specially designed for the Raspberry Pi 3 B+ (5-foot cable) Set of 2 Aluminum Heat Sinks CanaKit Quick-Start Guide