YesProbably.
There are parts of HTML5 that you can use right now, today. Forms for example. If you have <input type="email">
in a browser that doesn't support HTML5 (yes, even IE6) you will simply see the same thing you'd see if you used <input type="text">
. Yet on a browser that supports HTML5 form elements, you gain the advantages of the email
type: namely the client will error check the value with no extra JS required. While yes, you'll still need the JS for non-HTML5 browsers, you will have one more layer of validation in the supporting browsers.
Another question on this site provides a good overview of the new features available to you through HTML5 and CSS3. There's a lot of good data on forms in that question, too.
Because Internet Explorer (and older versions of Safari and Firefox, however rare they may be) do not support many of these features you are left with JavaScript libraries to fill the void. These include a performance hit (even though it's only for the browsers that need to use them) so be mindful of your users when employing them.
To mitigate the issues with lack of feature support, should you decide that these new features are worth it, use the following resources: