Unlike some earlier posters I do believe there is real value in xhtml 1.0 transitional. First it gives you more warnings on errors in the validator (I religiously check any page after every edit).
Sure enough MSIE runs decades behind, but that's no reason to stick with older standards.
And it allows real xml oriented tools to be used.
The documents comparing HTML4 vs. xhtml typically compare against a strict xhtml and there I agree: the browser side is not ready for that.
But if you do: make sure to be very strict about checking your pages and the doom scenarios they depict don't hold for you.
A browser should not dump you in quirks mode on a strict xhtml doctype, no matter what (it should pop an error if something is wrong), but quirks more is ingrained due to the past where e.g. images aligned with text baselines and transition was needed, so you still get it every so often.
Basically I add a link to the bottom of my pages pointing to [validator.w3.org...] that way verifying for yourself is an easy habit just after you view the page.