My dad had about a third of his tongue removed (26th Nov), and reconstucted using a flap from his forearm (+ neck dissection). His speech is far better than we expected. It is slightly slushy/slurred especially if he's tired and he struggles a bit with 's' and 'g', but is totally intellible, and as the swelling goes down it continues to improve.
But the bottom line is that however he sounds, he's alive!
Best wishes, Sara