[HTC One A9] Cashreedhar:
Received my Sprint version of the A9 yesterday, so far loving it.. I have been using HTC One M8 H/K edition (non-rooted) from 1.5 years and all my views on this phone will be based on my M8 and iPhone 6 which is my second favourite device at my house. Discovered few things, following are the key points:

1. Performance - Gaming (normal) has been very smooth and switching between the apps have been very fluid. Camera launches very quick and photos are taken lightning fast. I haven't noticed any heating issue or a battery drain at the rate of M8. However, it struggles to play a 4k 60fps which I noticed lately. Youtube native 4k playback has been very smooth.

2. Display - Display is very smooth (I am not sure what mechanism they are using, but it is really great) and I really love the 2.5D corners. Swiping from the edge is a fun as it doesn't hurt with a sharp edge on the side.

However, the display colors are not as natural as M8 and I really had a high hope on this, it looks bit fluorescent at Amoled settings and at sRGB setting it looks reddish (just like iPhone end Galaxy edge). After keeping my M8 aside and focusing on A9, somewhere I am adjusted to this new color.

3. customization - I really love the effect of HTC theme on the entire skin of the OS, unlike in M8 with sense 6.0 it was just a gimmick. The statusbar icons on Sprint version looking different than the gsm models, and looks really like a stock android status bar (it is my complaint and searching threads to change this off).

4. Design - Like all of us know, device looks even better than in the photo, 2.5D glass is a real beauty. Compared with my iPhone 6 (where the glass is bit floating and not very flat towards the edges) and this phone wins on the design. Camera placement is just right and fingerprint sensor is very fast. you won't feel like missing anything. Very premium in hand, and I can reach all corners in one hand, pretty impressed. haven't noticed slippery complaints like others mentioned, but I added a silicone transparent case, just to protect new phone from dust and scratches :D (which would go off in a week)

5. Camera - There are good and bad points on the camera. Front camera is very good and far better than my One M8 though both have the same 4UP technology, and I am not sure what makes it 4 times better. Discovered something last night which was never discussed in any review - In total dark night, just with the light of the phone screen (which was kept at low), I was able to take a very bright clear selfie, which is sick. I tried taking with M8 and and iPhone and black images captured. Does the front camera come with nightvision? I dont know.

When it comes to rear camera, I have complaints. I always used to touch focus and take photos of the focused object, but the camera struggles to focus and 95% of the times what it focuses is a wrong point, sometimes the photo is totally blur if I touch focus on any object. Also, I took few photos on both phones in the morning, M8 photos look more premium just at the capture, but obviously when zoomed in A9 is better because of the megapixel count. And the colors look more accurate in M8, but it could be because of the Amoled display which I discussed before. Also, I took few photos in the low light conditions of the morning, photos are really dull in auto mode. Raw mode is very impressive though, but haven't discovered much around that.

6. Battery - Battery has been very impressive, and its better than M8 so far. I haven't completed one full cycle but, with the activities I had on this phone and the battery backup is very good. But that is not all, when M8 receives marshmellow, it could beat A9 easily I think.

7. Sound - I am not really missing the front speakers but I am really missing the Harman Kardon sound quality in the earphones. I have not used the boomsound enabled M8, but the Harman kardon edition with the sound engine really had magic. Most of the time I listen to music, and boomsound just sounds like an iPhone or Galaxy, but with increased volume in the headphones which my ears dont like.

Overall, HTC One A9 is a great phone in my opinion and I just paid $399-$100 =$299 technically. Even if you don't consider the pricing aspect, this is a great phone with few limitations. For me the main disappointment is the audio and definitely nothing can beat the Harman Kardon engine. I will just wait for the Marshmellow update and see the performance and battery on M8 and looks like I will stick back to my M8 forever lol.

Note: My M8 had really serious problems for around 2 months (it all started with service pack update) and it use to be very slow, recently with service update HTC fixed it. But honestly what changed my M8 is Droid optimiser (which was recommended in HTC blog), that really changed my phone. I am not sure what magic it does, but all system apps are being taken care, even though I am not rooted and phone runs like brand new (including camera launches as quick as it was when I bought the phone). installed on A9 too, give a try. https://play.google.com/store/apps/details?id=com.ashampoo.droid.optimizer

Edit: one last thing, I had signal problems on A9 and the signals were not as strong as M8. Also, noticed the weak signal would lead to high battery drain. Downloaded Google connectivy Services app, which boosted the signal and also I was able to get the signal inside the tunnel, where M8 was not able to catch. https://play.google.com/store/apps/details?id=com.google.android.apps.gcs&hl=en