I believe it is, and in this blog post I shall point to just one of the features which helps to identify the sitter.
We'll be concentrating on the left eye (the sitter's left, that is) and, in particular, a distinctive scar immediately above the left eye. It's clearly visible on the "Wadlow", cutting down from above the eyebrow to slice through the outer end of it. Just in case, I'll provide another detail of the portrait, which brings us in a little closer.
There, see? The scar comes down over the left forehead, meeting the left eyebrow about halfway across. Something similar can be seen in the "Chandos" portrait of Shakespeare at the National Portrait Gallery:
It might look a little clearer in this detail of the above:
This scar was, apparently, something that Shakespeare bore for much of his life. The evidence for this, I would suggest, is visible on the contested skull of Shakespeare at Beoley in Worcestershire (detail of photo by Richard Peach for The Village magazine):
A photo of the Beoley skull, taken at around the time of the Second World War, shows the scar over the left eyebrow very clearly:
Just in case, here's a detail of the same, showing the left eye socket and the scar above it:
So, Shakespeare had a scar over his left eye, cutting down over his left eyebrow, which is precisely what we see on the "Wadlow" portrait.
But, wait - what's that you say? The Beoley skull was "proven" to have belonged to a mysterious, unknown female in her seventies and can't, therefore, have been Shakespeare?
Hmmnn ... tell you what: let's check one more image.
This is a detail from a facial reconstruction of the contested Shakespeare Death Mask in Darmstadt, Germany. There it is, just above the left eyebrow - a scar which runs down to meet the eyebrow about halfway across. The same reconstruction of Shakespeare's face from the death mask, only taken at a different angle, shows this scar very clearly:
And, for comparison, the scar on the death mask facial reconstruction alongside the scar on the Beoley skull:
They look pretty much the same, don't they?
Well, here's the odd thing. That facial reconstruction of the death mask was done by Dr Caroline Wilkinson - the same expert who claimed that the Beoley skull was that of a woman in her seventies!
Admittedly, the Channel 4 Shakespeare's Tomb documentary, shown earlier this year, did rather railroad Dr Wilkinson into making that statement ... but maybe if Caroline Wilkinson had compared the skull with her own facial reconstructions of Shakespeare, she might have been less certain in her analysis.
The scar - on portraits, death mask, facial reconstructions and the Beoley skull - is one of Shakespeare's distinguishing features.
That, or a massive coincidence, requiring us to believe that the only skull to have been identified as the "veritable skull of William Shakespeare" actually belonged to an unknown septuagenarian, even thought it has exactly the same scar as Shakespeare had!