There is much in the news today about this portrait being a true likeness of Shakespeare:

 Up to now only two images have been accepted as authentic representations of what Shakespeare may have looked like. One is the engraving by Martin Droeshout published in the First Folio of 1623. The other is the portrait bust in Holy Trinity Church, Stratford-upon-Avon; the monument is mentioned in the Folio and therefore must have been in place by 1623. Both are posthumous –- Shakespeare died in 1616. The engraver, who was only in his teens when Shakespeare died, must have had a picture, until now unidentified, to work from. Professor Wells believes it to be the one he has revealed today and that it was done from life, in about 1610, when he was 46 years old.

[From the Shakespeare Birthplace Trust website]

The portrait [now called the Cobb Portrait after the owner] will be on public view at the Shakespeare Birthplace Trust in Stratford-upon Avon beginning April 23, 2009.

See this article at Time.com;  and another at the NYTimes for a full report.