After the Nexus 5 was announced, I decided it had enough to be worth upgrading from my Nexus 4. In particular, I liked that it had a plastic back (instead of glass), a 32 GB storage option, and would get me LTE on both AT&T or T-Mobile.
Lots of tech sites have since posted their reviews, so this may cover ground that has already been tread, but still, here are some thoughts now that I've had the phone for a few days.
From a hardware standpoint, the N5 feels like a big step up from the N4 in a lot of ways, yet iterative in others. The camera is still only so-so compared to other devices on the market, like the iPhone 5[SC] and some of HTC's offerings. It does seem like it fares better than the N4 did, but I'm not much of a photographer so it's probably going to be hard for me to see the nuance in a lot of situations. Subjectively speaking, though, shots look a bit sharper and have better color reproduction, especially in low light.
The screen is gorgeous, but then that's pretty much what I was expecting from a 1080p, ~5" screen. I had no real qualms with the N4's screen on the whole, but this one really looks sharp. One thing I do miss from the N4 is the curved glass on the sides of the screen. It was one of those small touches that really made the front panel feel nice, whereas swiping side-to-side on the N5 means you simply hit your finger against the bezel. That aside, it's clearly the superior screen.
However, I think the part of the hardware I like the most is probably the back. I've never been a fan of the glossy plastics used in Samsung's phones, and the Galaxy S4 didn't really improve on that. Similarly, though I didn't mind the glass back of the N4, it was always a little bit weird to watch it simply slide off of surfaces that I had assumed to be level. The soft touch plastic on the N5 is awesome. It feels very similar to the back of my Nexus 10, and it's very grippy and comfortable.
The last big improvement, for me, is the addition of more LTE bands (technically, any LTE bands). I've already jumped from T-Mobile to AIO Wireless since I went off-contract, and one of the big losses in that transition was LTE. Around my area, AT&T has rolled out LTE on band 4 in some places, but not most, whereas T-Mobile's rollout was very good. With the N5 I don't have to worry anymore, because I can get AT&T's larger LTE network bands as well as band 4. It's really freed me up to do whatever I want as far as my carrier is concerned.
Android 4.4 - KitKat
Of course, one of the big selling points of the Nexus line is that they come with unaltered Android installed (often called "AOSP"). The Nexus 5 is the first device to ship with Android 4.4, which has made a bunch of notable changes. The most obvious difference is that the UI has been greatly restyled, substituting whites and grays for the blues that been commonplace circa Honeycomb. It feels very clean, although part of me misses the blues a bit since it's generally my UI color of choice (when given a choice, anyway). Google also made many of the icons a little more stylish, such as the Settings icon that has now become a gear with a sort of flat, pastel look to it.
KitKat also adds some nice improvements in the Settings beyond the icon change, such as a new NFC payment implementation and the ability to change your default launcher right in the settings. Printing options also live here, though I haven't really tested them at all since I generally don't have a need to print things from my phone.
Funilly, the feature I've found myself loving the most is one I hadn't seen mentioned anywhere: you can now dismiss an alarm from the notification pane before it goes off. This is a pretty small feature, but I have to say, I freaking love it. Now if I wake up 10 minutes before my alarm I can just dismiss it, instead of having to disable it and re-enable it later (clumsy) or wait around for it to go off (annoying). Google may not have thought this was important enough to mention, but it was a very pleasant surprise.
Also in line for an update was the Email app, which now looks very similar to the Gmail app. It's nice if you use non-Gmail accounts, I'm sure, but I don't use it. Still, it's a big improvement over the suck that was the old Email app.
Overall performance has been excellent. The few games that I play are silky smooth, and all of the ordinary functions like switching apps and scrolling through pages of text are pretty much instantaneous. Whether it's the Snapdragon 800 or KitKat (or both) is hard to tell, but whatever the case, the software feels very snappy.
The other big change with the Nexus 5 is that Google has re-written the Google Search app to effectively make it the default launcher. In some ways I could see this being a very attractive option for people who are really in to Google's ecosystem. You can use the "OK, Google" phrase from any home screen to use a voice command, and Google Now sits to the left of your home screens (ironically enough, iOS recently moved spotlight away from that same location).
On the other hand, the launcher just feels too inflexible to me, and I've not even been using it. The number of home screens you can have is seemingly unlimited, but the "home" one is always the leftmost panel. This isn't how I want my screens to be arranged, but I have no choice in the matter, because "home" always goes immediately to the right of the Google Now panel.
I'm also not a big fan of the icon grid on the home screens, or on the app launcher. The icons are way bigger than they are on other launchers, and it makes them feel kind of awkwardly cramped. You also can't get adjust the number of rows/columns in either, and the app drawer no longer contains widgets. I thought that was a nice idea when it was first added, so I'm not sure why Google thought to abandon it now in favor of making you long press a blank space on a panel to add a widget.
The other big update is Hangouts, which now supports SMS and MMS alongside the typical IMing. I'm not sure how I feel about this one yet, but it's starting to grow on me a bit. I use Hangouts a lot anyway, since most of my friends are on it, so having just one app to deal with is kind of nice. Conversely, having SMS relegated to separate conversations seems a bit clunky, since it means that a conversation that spills over from one form of contact to the other will get split between threads. This doesn't happen too often, but when it does, I feel like I would prefer to have everything in one place. Arguably this would make it a little more complicated to send a message to someone - since, in theory, you might not know which protocol was being used - so I might be okay with this design in the long run. We'll see how I feel after a few weeks or so.
Obviously this isn't an entirely in-depth review, but hopefully it provides a bit of a broad view of my impressions of the Nexus 5 so far. Really, it's a great phone, at an even better price. If you're looking to go off-contract, which I highly recommend, then this is the best bang for your buck out there, without a doubt.
If you eat and breathe Google, it's a great device for you as well. There are some bumps in the new Google applications, but they still function perfectly well, and really just feel like they need a bit more polish to be truly great. All in all, I'm very pleased with the N5, and definitely think it was worth the upgrade.