I agree with Andy,

I use it as a guidance tool on any website i build. It serves a purpose, to check things are understood how they should be by a predetermined standard. But like any other automated tool it compares to set requirements that cannot always be met and cannot identify and ok these exceptions.

As long as you understand the error its pointing out and why its pointing it out, and know that despite this the code is rendering correctly and all outcomes are working as expected then there is no problem.

From an SEO stand point, aslong as google see's your site how you want it too i think it is a very very minor factor. Hell all of google returns errors of some variety.

Rand,

I am a UK user.

I just went onto the keyword difficulty page and it said it is being removed from June 2nd to be replaced by the keyword explorer tool. Whilst I welcome this change as I love the keyword explorer, as a UK user i rely on the keyword difficulty tool for volume metrics as they keyword explorer doesn't yet show these for the UK.

Why the haste to remove this tool? Its a vital part of the puzzle for me until the explorer is fully operational. Could it not stick around until the explorer is fully functional?

Thanks