I started out with a DroidX back in the early days (technically I started with what I believe to be a Nokia 2160, then to a SonyEricsson P800/910, then a few Blackberries, and then to a DroidX). I graduated to the Galaxy pseudo-Nexus on Verizon and then the Nexus 4 still on Verizon via a MiFi device that turned Verizon into what I need them to be, a big fat LTE-everywhere pipe with no bloat and no phone control. The OnePlus One is my first foray into the non-Nexus lineup in a while, and so far I'm pretty happy.
The hardware does feel well-built. I skimped and got the 16GB model, never having had any serious space issues with my 16 GB N4. I find the phone a little large for me, but I felt the same way about the Droid X when I first got it and now smaller phones seem...smaller.
The screen is nice, but my old eyes don't see much difference between 1080p here and 720p on my old phone. Screens have exceeded my ability to discern pixels long ago.
I have yet to really try out the camera, especially to compare the stock app to the Google app quality. From the few night shots I've taken, I'm not impressed compared to a Df (for some reason a 4-figure single-purpose DSLR seems to out perform a $350 pocket computer which happens to have a camera), however the daytime shots seem much nicer than my N4 could ever produce.
There are also physical (well, dedicated capacitive) buttons. I don't tend to like this, especially since they're backwards - home in the middle, back to the right and menu to the left like a Samsung instead of the Back, Home, Task Switch I'm used to on the Nexus lineup. I do think the layout works better for right-handed users since back is much more common, but it's different from the Nexus "official" layout (bad) and I'm used to using the task switch which is a lot harder to do across the screen with a long-press. Still, I'll get used to it.
Something that you won't find in any spec sheet is the "upside down" USB port. Most Android phones have the small end of the USB connector up, but most Android tablets have the large end up. The 1+1 is tablet style which matches more of my devices. However, I have a few generic docks for other devices that would need to accept the 1+1 backwards. Luckily, I charge my main phone via cable instead of dock.
I fell out of the ROM craze shortly after Jellybean hit and I realized that stock was now well into the "good enough" stage for me. I've run CM in the past and found it to be a "kitchen sink" ROM, tons of little settings and tweaks that I didn't care about. The CM11 version for the OnePlus is a bit more stock, but some of the behaviors are a bit different from my 4.4.4 devices (I initially missed the WiFi dropdown not toggling WiFi but opening up settings, however long-pressing brings up the settings menu). Since I'm forced into a custom ROM I'm tempted to start over with Paranoid Android's build, especially with the tablet-like size of the OnePlus One.
First of all, there's a decent chunk of bloat in the OnePlus defaults - mostly Chinese alternatives to the Google Apps. However, they're mostly removable (except for Apollo which is CM's music player).
Most of the apps I use are just the apps I use everywhere and aren't anything special. However, a few of them are particularly useful for the OnePlus.
Ingress Of course, those of you who play Ingress will care a lot about this. Aside from some minor scaling issues because of the DPI switch and font size increase (see below) Ingress has been working very well. Decent battery life and the only quirk I ran into was the compass stopped working suddenly. I have no idea why, but it was only Ingress that it broke with (dedicated compass apps worked just fine, but Ingress had me always pointing North) and an unscheduled factory reset seems to have fixed the issue.
DPI Changer Not a very pretty or intuitive app, but it fixes the biggest issue I have with the Now Launcher and may obviate the need for installing Paranoid Android. By changing the DPI from the default of 480 to 280 and upping the font size to 115% I find I have a good mix of extra space and readability. With the primary goal of tricking the Now Launcher into thinking I've got a small tablet and using the same rotation UI as my N7. 240 will make it think I've got an even larger tablet and use the N10 rotation scheme. Under Settings --> Display you can enable 180 degree rotation as well as lock-screen rotation to complete the tiny-tablet experience.
MultiLing O Keyboard Always one of the first things I install, it's a nicely customizable keyboard which has a float mode meaning in landscape you don't have this huge, wide thing taking up all your space. It really makes use of the large screen and high pixel count on the 1+1.
#MirrorEnabler will restore a feature from the Nexus line that enables you to mirror your screen to a Chromecast. Download and install the APK, under Settings --> Display --> Cast screen toggle the switch to "On", and then in the app enable Mirror Status and QuickSettings Mirror. Now you should have a Cast Screen entity in the dropdown. It's a little buggy and slow, but it's workable.
I purchased the 1+1 sans invite from Oppomart, this is the Chinese version so if you're not as enlightened as I am (Ingress pun intended) and just care about WiFi access because your carrier is just a fat, dumb MiFi-enabled pipe please check your frequency bands. It came with Cyanogen pre-installed, and there was an immediate OTA update available for it. The only mildly annoying/disturbing things were that I needed to perform a factory reset before it would prompt me for my Gmail account (of course, I could have added it manually but you don't get the factory-fresh wizard) and the phone seems to be rooted. I needed to install SuperSu to manage rooted apps, but I never intentionally rooted it.
I'm now using a wallet case with my 1+1, so far it seems wholly adequate. The card slots are a bit loose for a single card (let alone something like a MetroCard) but add a small number of credit cards, a license, and a there's a pouch for a few bills (folded, it's a little too small for US dollars to lie flat) and it may be a decent wallet replacement, at least for casual use. I also got one of these to put my laundry machine card on my laundry basket, the pouch is a stretchy fabric and fits my trivial number of keys. As another trick, use a ziptie to fasten them together, it's a lot less bulky than a keyring and you can leave a little tag by which to grab them.
The OnePlus One is pretty much Nexus-level hackable as near as I can tell. Getting into FastBoot mode is pressing and holding the Volume Up and Power for a few seconds.
The standard Developer Mode trick of going to Settings --> About Phone and tapping the build number repeatedly works.
I usually like changing the DPI to 280, otherwise things are too big and the Now Launcher won't rotate. While you're in /system/build.prop you can add this line to allow lockscreen rotation: