According to Wikipedia, Flash has been in existence since 1996 and, because of this, has a strong base of developers and users. According to Adobe statistics, Flash has reached 99% penetration on Web browsers, while HTML 5 has a 40% penetration.
The latest version of the Adobe Flash Player runs on Microsoft Windows, Mac OS X, Linux, Android 2.2+, RIM QNX and Google TV. Earlier versions run on PlayStation 3 (Flash 9), and PSP (Flash 6). Adobe Flash Lite runs on Wii, Symbian, Maemo Linux, Windows Mobile, and Chumby. In contrast, some video sites, including YouTube, and blip.tv, have implemented a degree of experimental support for HTML5 video. Steve Jobs noted that Flash is not an open standard – it is controlled by Adobe Systems, whereas HTML5 is largely controlled by a committee (WHATWG) made up of three companies: Opera Software, the Mozilla Foundation, and Apple.
Some users have complained about the relatively high CPU usage of Flash for video playback. This was partially because the Flash plugin did not use the GPU to render video. Adobe has responded to some of those criticisms in the 10.1 and 10.2 releases of the Flash plugin by offloading H.264 video decoding to dedicated hardware and by introducing a new video API called Stage Video. In addition, the use of the newer ActionScript 3.0 inside Flash movies instead of the older ActionScript 2.0 improves code execution speed by a factor of around 10. But older websites that use ActionScript 2.0 will not benefit from this. Another reason for poor Flash performance is that some Flash developers incorrectly code their Flash files which can be a problem with “HTML5” animations as well.
Constructing Flash websites using Adobe tools is relatively easier than with integrated development environments for CSS, HTML, and JavaScript. However, many of Adobe’s tools are expensive. It obviously takes time for tooling for HTML5 to get on the market. Adobe has released a first version of a Flash to HTML5 conversion tool for existing content and are working on creating new tooling for HTML5 as well, like Adobe Edge. Because HTML5 is an open format (like SWF) any toolmaker can build them, the first ones like Hype are already on the market.
To help you decide between the two, OneMoreLevel.com has crafted a side-by-side comparison of the two.
Is anyone still using Flash for anything useful? I think Adobe will kill it off soon. It has lost its use since mobile phones didn’t support it and because HTML5 rocks and doesn’t have security holes the size of Nebraska which Flash has. And Adobe is trying to keep it over the water by releasing one version every week with new holes. Good luck on that.
Some of these seem like straw-man arguments – of course the incumbent technology has more games. Why is that an advantage?
Also, the 2 technologies versus 1 file format advantage is reversed if you have web development experience.
As for my own straw man argument:
# OF FATWAS DECLARED BY BIG-ASS COMPANIES: 0 versus 1