As a fiddle main for the longest time from my main account to now, Here's what I can tell you:
He doesn't need anything more than a Visual Update. His kit is fine. He's really easy to counter gank early if you know what you're doing, and he is easy to kill if you have jungles and channel sweet spots warded.
I'll breakdown his kit:
Q - Fear for about 2 seconds at max. As a secondary support champion, his Q is unique since it is one of the only abilities in the game that has no damage for a champion's Q ability. His Q is very helpful against diving and mobile champs, such as Garen, Master Yi, Rammus, etc. Another great thing his Q does is that it cancels Channels. It's a very underrated and helpful ability, but not super effective if you're the jungler. My verdict: Balanced and Underrated.
W - The Drain is Fiddlesticks signature ability. I think it has the title of being the channel with the most damage that isn't an Ultimate in the game. He heals from his W, but he is also very vulnerable with his W. If he is draining one guy, he is unable to worry about anyone else around him. In team fights, Drain is only really useful during Fiddlesticks' Ultimate, but even that isn't guaranteed if you're going to Zhonya's. My Verdict: Balanced but Threatening in 1v1 situations.
E - To be completely honest with you, The silence from this ability is one of the remaining few 'click to silence' abilities. We used to have a Click to Pull Blitzcrank, a Click to Stun Taric and Sion, a Click to Slow Swain, and a Click to DoT Swain. The Click to Silence may be an edge that Fiddlesticks has over a lot of champions, especially since it is a great poking tool and damage dealer. This is the only ability I would agree with any of you on that needs a change.
My Verdict: Outdated and Overpowered.
R - Crowstorm is also a signature ability of Fiddlesticks, but the W I think is more exclusive to his character than the Crowstorm. Fiddlesticks' ultimate is such an amazing ability for it's Team Fight potential, damage, and assassination capabilities. This ability does not deserve any rework whatsoever. It may deal a lot of damage, but against a team that knows how to counter it makes it useless. Warding Channel Sweet spots (Raptors, Gromp, River bushes, Buffs, pits, bush behind pits, etc.) Make it really easy for a champion on your team to either burst him down or silence him. Taking him out has a critical affect on the team fight because his team would be expecting his ultimate to carry those fights.
My Verdict: Balanced
The E could be a skillshot if anything, but overall this champion only needs a VU.