As someone who owned the SP3 - a device I loved at first, but then with Windows 10 that whole experience went downhill, here are my thoughts on the SP4 after 4 days with the unit.
Bottom Line: MS released SP4 about 1-2 months before the software and drivers were ready.
Pros:
- New Thermal system is much better, stays silent for most tasks - my SP3 kicked on the fan way too frequently
- Cooler to hold in your hand - even when the fan is on - heat is well distributed
- I can use steam in-home streaming without the fan kicking on, this is awesome (SP3 always had fan running for this task)
- Brightness - this is an amazing display - watch a fullscreen video, set the brightness to 50-75 for some very nice contrast and visuals
- Magnetic PEN attachment is strong and effective - I can now keep the PEN attached to the unit at all times
- Better overall performance, especially the iGPU - can play some 2-3 year old games quite well, but you have deal with some CONs
- It is noticeably lighter than the SP3, but not game changing
- Windows HELLO is awesome - when it works
Cons:
- BUGS out the wahoo - hopefully most will be resolved, but they released SP4 too early
- Video driver is a mess - known issue by MS
- Realtek audio driver causes connected standby power drain (for me) - not sure if a known issue or not
- Battery life has been fairly poor for me - not going to quote a time, but I feel like it is 1-2 hours less than what I expected from my SP3 so far
- Unreliable sleep mode - went to bed last night with 40% power in the battery, woke up to a completely dead SP4 SLEEPSTUDY confirms multiple causes - display driver and realtek audio driver seem to be leading candidates
- I've had a few issues required full reboot (touch stops responding) - and one time the unit would not wake after pressing the power button approx 6 times
- WHEN the system needs to kick on the FAN, it's a very loud at max RPMs. If you plan to do processor/GPU heavy tasks, prepare to put on some headphones to cover up the extremely loud FAN (i.e., in a game)
- Windows HELLO seems to work about 80% of the time, even in the dark, but at odd times it seems like there is a driver crash or something - but it doesn't know about it (IR light will come on, but you can't see an image of yourself in the Settings at all).
I think two months from now, we will likely have a much better user experience, once drivers are mature, bugs are squashed, and I'm betting MS can do something about the fan ramps in the firmware so that it is less aggressive to hit max RPMs under 30-50% CPU load. That said, I'm on the fence over whether I want to wait for this to sort itself out. I'm a bit sour that my great SP3 went south with Win10, and I feel like MS is taking their consumers for granted with the entire "Windows 10 is a working product" concept by ramming it down everyone's throats who were fine with Windows 8.