Gillon is a much better ball handler. He's quicker / faster. He's a much better PROVEN scorer. He is a better shooter, with significantly deeper range than Howard. He is a better finisher on drives. He's a better mid range scorer, both on pull ups and taking it to the tin. He's better against the press.
There are many facets of his game beyond shooting where he is "better" than Howard.
Also, I'm not sure which highlights you saw where you didn't get the impression that he was an ankle breaking water bug--he is.
Your assessment in the last two sentences aren't on target. Yes, he played at a mid-major--doesn't mean he can't ball, or that our expectations should be shaped by where he played previously. Prepare to be surprised--he's a much better player than you give him credit for.
And the news that Howard has improved quite a bit from last year is great news, as well. A strong, versatile backcourt is a boon to our team's postsesason chances.