I don't get it >>> ^O^ ?

It is a meme in Japanese BBS forums, where the face \(^o^)/ is generally associated with the words 'Owataaaa~' Which means 'It's the end~', which, depending on the situation, means 'Death is imminent and un-avoidable~' or 'This is nearly finished~'

So, the artist could be making a statement that he has nearly finished this time consuming drawing.