I just started with Phaser last month and it's great. Your tutorials page was a great reference for me(http://www.lessmilk.com/phaser-tutorial/). 2.4 looks great. Have you experimented with the support for boned Creature animations? I've ben testing out Creature for 2D skeletal animation and it seems quite nice.
It's my favorite library for building small video games for fun. I recommend it to anyone who wants to build a 2D web game. It has good docs and the code is fairly simple to read and write.
* Impact is a lot more low-level. If your game is complicated, you will have to get into the weeds of the canvas API.
* Phaser supports canvas and WebGL. Impact supports canvas exclusively.
* Impact costs $99. Phaser is open source.
* Impact rarely ever receives updates. Apparently the creator is working on 2.0, but nobody knows if or when that will be released. Phaser is updated very frequently.
* Phaser has the edge in terms of popularity. You will find a lot more articles and books for it.
* Phaser has batteries included. Impact is more bare-bones.
* It can be a pain to keep your local changes synced with upstream changes in Impact unless you go through a bit of hassle. (You will -probably- need to modify Impact's core if your game is complicated.)
* Impact has a level builder and some other tools out of the box. I personally don't use it. Tiled is better, and Phaser has good support for Tiled. Actually, I've had better luck using Tiled in Impact, but it required writing a lot of custom code. Most people will probably have more luck using Tiled with Phaser.
* Impact is a lot faster in my experience, even with WebGL enabled in Phaser. YMMV.
* Impact has far superior support for high DPI screens last time I checked. (Disclaimer: was a year ago.) Getting stuff to look good on retina screens in Phaser was hellish and things would randomly break.
* The learning curve of Impact is extremely low. However, you will feel constrained for bigger projects, which may require lots of custom visual and audio handling.
* Impact uses its own module system. Using browserify or webpack with it isn't really feasible.
This, this is the best JavaScript game framework. Been using it for a few years and it never let me down. It is constantly updated and has lots of examples to get you started.
I have just created a small game and exported it to an android .apk and easily runs at 60fps on Nexus 7 (2013) at 1920×1200 resolution.
I use CocoonJS: https://www.ludei.com/cocoonjs/ . You just upload the archive with your HTML5 project and it compiles it for you and gives back .apk and iOS files.
Seeing updates for Phaser makes me so happy! It really is a gem of a library.
A nice thing about it too, is that it is very easy to make something that is compatible with both desktop web browsers and smartphones. When presenting at a game jam or hackathon, it's nice to be able to push what you've done onto GitHub pages and encourage your audience to try things themselves.
As far as I remember, the only requirement is that you host it on a server of some kind. I haven't tested it, but I don't see any reason you shouldn't be able to throw it up on a Github page: https://pages.github.com/
That would depend on whether you need any server-side application for your game. Obviously, if you want to build some kind of multiplayer game, that's a yes, and your options depend on the technology you want to use for the backend. Otherwise, if the game sits entirely in the client, you can get away with just serving static assets from something like Amazon S3, which costs very little at all, or perhaps even Github pages.
Hm, I had a very different experience. The extensive example library makes the Phaser documentation excellent, in my opinion. The API docs are average, by no means terrible. I've used Phaser, Unity, or SDL for various projects and I've hit the documentation fairly hard for each, so I hope I might have some perspective on this.
I've had a completely different experience. Phaser is one of the easiest to use JavaScript game engines and the documentation is well written, also they have plenty of examples. If you prefer to learn from a book, there are also a few books available.
If you want to learn more about Phaser, you can check out my Flappy Bird tutorial here: http://blog.lessmilk.com/how-to-make-flappy-bird-in-html5-1/
I also wrote and self-published the first book about Phaser: https://www.discoverphaser.com/
Let me know if you have any questions! :-)