To keep it short and sweet, I love the play making ability, but his coverage skills for a FS are pretty lacking.
Pro Football Focus has him ranked as the 69th out of 86 safeties this season, mainly because of those coverage skills.
From Walter Football:
Of the safeties who have played 800-plus snaps this year, he's surrendered the eighth-highest completion percentage. He allowed four touchdowns this year (tied for fifth among safeties) despite the amazing front seven he has in front of him. He's tied for sixth in penalties among safeties this year. If he played behind a mediocre front seven, he would be exposed. Those who just look at stats and Pro Bowl voting might think Goldson is great, but he's just a backup at best.
I guess the team's judgement is all that matters, but these two bits of information are quite telling.
I just see so many traits of a SS in him. I guess he has value in the right scheme because of the play making ability and big hit ability, but at this point, I'd franchise him, rather than sign him to the long term deal, based on what's available.