[One (M8) General] Travisimo:
I just bought my One M8 (gunmetal) the other day and immediately converted it to a GPE when I brought it home. I was actually going to buy the GPE from the Play Store, but I wanted the gunmetal variant (GPE is only available in silver). I was delighted to discover that the GSM version could be converted to a GPE. So while I cannot compare my M8 running GPE RUU to Sense (I really didn't even use Sense except to turn on USB debugging), I can compare it to my Nexus 5 running the Android L Preview.

I have to say unequivocally that the One M8 hardware combined with stock Android is a match made in heaven for me. I've been using the Nexus 5 for a while, and though I love the phone and stock experience, the battery life was pretty bad. Installing the L Preview was fun and I've been running it as a daily driver since it came out. I'm still using it on wifi, so I'm able to directly compare my M8 to it.

Here are my impressions of the GPE 4.4.4 converted M8 compared to my Nexus 5 running Android L Preview:

- With my M8 on Dalvik, there is a bit of stuttering in apps. The notification pane is smooth, as is the app drawer and launcher (using Nova). But when using apps (particularly Facebook, Google+ and even the XDA forums app), there is stuttering when scrolling up and down. It's more than just the universal stutter you get when things are loading in from the network. It seems like either the CPU is underclocking or perhaps the stuttering you get without Trim optimization. It's not worse than I've seen on other phones, but the Nexus 5 running the L Preview is buttery smooth (perhaps the smoothest experience I've seen on Android).

- I switched my M8 to ART and it got much smoother, pretty much on par with the Nexus. Didn't think it would make much difference, but it certainly did... though now I miss my Xposed modules (sure hope the devs will be able to port it to ART). So now I have to choose between a slightly lagging device running Dalvik with more customizations via Xposed OR getting a smoother experience on ART while losing my customizations.

- I have not experienced any issues with the camera other than a bit of finicky focusing at times. But I've been used to using the Google Camera interface on my Nexus, so I feel right at home. I have to say that the M8 camera is definitely better in low light. Of course, there's not as much detail when cropping or zooming in because of the lower resolution, but quite good for sharing on the web or for small prints (I still remember my Nikon Coolpix 950 that was 2 megapixels and quite popular back in the day). The front-facing camera on the M8 is spectacular relative to the Nexus' poor selfie camera. I am getting a small bug in the Google Camera interface on the M8: if I choose the 4:3 ratio at highest resolution for the back camera, the viewfinder is not masked properly (doesn't show the right ratio and the photos taken in this mode are framed differently than I shot them).

- Battery life on the M8 running GPE is phenomenal compared to my Nexus! My typical usage is to take my 100% charged phone to work and use it for playing podcasts at 1.5x speed for about half of my shift. I also use my phone for hotspot for about 30-40 minutes along with some screen on time during breaks. There's no wifi at work, so the phone is on the cellular network the entire time with pretty poor signal inside the building. After my 8-hr shift, I'm typically at 30-40% with my Nexus and with the M8, I'm leaving work with appx 70% battery. Both phones are configured to use High accuracy location reporting and I use Google Now quite extensively.

In summary, I am quite pleased with the GPE M8 conversion. I was a little annoyed by the minor stuttering, and I'm still debating whether to stick with ART or go back to Dalvik for my mods. I suppose it'll be a moot point once Android L comes out because I'll have no choice but to be on ART... and hopefully by then, Xposed will be updated.