Of course I embraced HTML5, but since this was written as a top 10 of why I _should_ use HTML5 now, I'll try to refute that top 10 for reasons of why you _shouldn't_ use HTML5 right now:

10. Accessibility.

HTML5 sure has the potential to improve accessibility, but.WAI-ARIA guidelines are in draft mode. It will be several more years before assistive technologies fully support HTML5 to the degree they now support HTML4 and all your users will run on browsers that support HTML5.

"Upgrade to the latest version of Chrome to view this HTML5 demo" isn't any more accessible than prompting a user to download the latest version of Flash 5.

WAI-ARIA was needed to combat the accessibility problems that ajax-rich/click-rich web applications introduced. Part of this HTML5 and forward thinking is responsible for accessibility problems, not a cure.

Requiring javascript support (shiv) or a web-kit browser from a user, for laying out a web page isn't all that accessible.

9. Video and Audio Support

The author called flash video implementation a hassle. So what does the author call a flash video fall-back, with a <video> tag, and your video encoded in .ogv, .webm, and .mp4?

And javascript feature detection to decide which to show? And a way to implement custom controls for both flash-video and html5-video?

And since you want accessibility how about flash and html5 captions? Descriptive Audio?

And Yahoo searchmonkey RDFa that you already used for your flash video and schema.org for your html5 video? Incompatible.

How long did it took for Flash to support webcam video and what is the current support state of <webcam> for html5? Video and audio support is what Flash did/does best.

8. Doctype

It is short and simple, right? Why not <doctype>, or why not leave it out all together, if you can't be bothered as a HTML web developer to remember, store or copy-paste a doctype?

And RDFa with a html5 doctype?

7. Cleaner code

Faulty example.

Why not
<ul id="subnav">
<li>..</li>
</ul>

How is that less clean than
<nav id="subnav">
<ul>
<li>..</li>
</ul>
</nav>
?

6. Smarter Storage

Only works for local storage capable browsers, so off limits for app critical functionality, unless you don't care about that. If it was so smart, why can't I store a 15MB movie on Safari mobile?

Do you want to bother your users with a pop-up that says: "This website wants to store stuff in your local cache" while storing stuff like preferences in cookies is much more silent.

And how secure (for your privacy) is local cache and ETags when it can be abused for tracking?

5. Better Interactions

"Better" Interactions. Better how? "It can do everything Flash was able to do in 2001, but better". Also better than Papervision3D from 2008?

4. Game development

I don't need to switch from Flash to HTML5 to get Game development. I wouldn't switch from Flash to HTML5, because better game development.

"If you’ve built Flash games before, you’ll love building HTML5 games."

If you were to poll game developers, this would likely be a very unpopular statement. I know it certainly doesn't apply to me.

3. Legacy/Cross Browser Support

Again, no reason to switch to HTML5 from HTML4. It would be a reason _not_ to switch, if it didn't had legacy browser support, but that doesn't make it a game changer all of a sudden.

And a browser conditional statement ("if lt IE9" or "if Windows XP general user"), followed by a javascript hack, isn't native legacy support. It is just what it is.

2. Mobile, Mobile, Mobile

HTML5 for mobile will be great, and this is a good reason to switch and fully familiarize yourself with HTML5 as a webdeveloper. Responsive design et al was already possible with HTML4 though, but the author is correct in saying html5 is important for mobile.

I am not really waiting to get "apple-touch-icon" approved as a HTML5 standard, but there is no denying that the future of HTML is in the hands of the big companies now.

1. It's the Future, Get With It!

Sure, that is why I am already implementing HTML6 on most of my clients websites. The specs are a little rough around the edges, but at least I made my clients websites future proof. ;)

It seems you are advocating more of a switch to dynamic HTML5 web apps.