I do like Guyton. I don't think hes a starter.
According to PFF, in 106 pass rushes last year, GG had 1 sack, 7 QB hits and 8 hurries. I would venture to say that many of those came on the blitz. GG is not a hand on the ground pass rusher but may have value with his burst to bring some pressure up the middle. He has shown that ability in a few games (Buffalo and a few others IIRC).
You would think with his speed and quickness, he'd be better in coverage but he's not. Again, excellent in spurts (Leon Washington in 2008) but statistically, hes not good.
Again, on both points mor eplaying time may be what helps him improve.