I feel like he was tier 4 in lane, and tier 3 when jungled- but he is moving up 1 tier now with new patch change. Just the small change to his Q- he can farm that to get it up much higher.
Why he might be better than people suspect...
Frozen Gauntlet- it synergies well with him, and it means that once he gets on you- he sticks on you.
Muramana- with the changes to it- he can easily get it fully fed out, and get a LOT of ad from it- and it can be the ONE item that he needs for offense, giving you 80-100 AD means you don't really have to buy anything else. It also works well with gauntlet giving you even more mana. It gives him the ability to burst out a 1000 dmg Q without tons of farm or a crit.
Armor/Resistances are more expensive and health is cheaper- his basic kit is pretty beefy already, and you don't see a lot of bruisers with % health dmg- % health seems to be the key to winning vs Singed/Darius/Olaf/Cho which dominate the scene. The torch works well on him, you don't need to build a LOT of AP either, just the torch/sheen and his ult gets the extra 1% + the torch %. Hell his E starts to actually hurt people at this point as well, and often a lot of these bruisers don't kite- they sit and fight it out. I've seen this with Malz too, on this map, having a zoning tool that does dmg- the AOE "no go skill" is SUPER vital when fighting over altars which are always being contested.
We don't see a lot of ADC's- which kite him and are his bane, we see a lot of champs that LOVE to sit and fight. Darius once engaged isn't going anywhere, he is committed to the fight. However you also don't always have a great target for your Wither because not a lot of these champs build ANY attack speed- it becomes just a great slow.
It depends on the Q change- if he can get 6 from the big wolf, 6 from the golem, and go to a lane and just steal the cannon for another 6, you are getting enough farm that way.
Build: G. Lantern -> Iceborn Gauntlet -> Muramana or Torch -> Randuins/Sunfire -> Boots of Choice -> Attack Speed Item (wits end or static)
I've also done well with the hydra on him, and then all defensive items.