Yeah, it's a 1.5 second channel, but it's got a deceptively low cooldown and at max level it's a 5-second knockout for EVERYONE in its also surprisingly large AOE. Yeah, it's about half of Fiend's ult (if even that), but think about it... That's still a lot.
Even more so, that AOE and stun can have two separate start locations, since both the spirit and the titan himself do the same deal, thus covering a significantly larger area and potentially locking down escape routes. Also, the spirit CANNOT be stunned, silenced, killed, or anything else done to it, meaning the channel can't be stopped unless they hit the real man himself.
He's more interesting for early ganks though, both because he can chase like a bastard by placing his spirit ahead of the enemy and then stomp their escape route, or even just getting the spirit to bump into them and a few creeps and give him a big speed and damage boost (I've built Mask of Madness a couple times on him just to capitalize on this).
His ult is a weird one though... HUGE range with a sucking effect, but an eternally long charge-up time. The fun bits, however, are that it deals percentage-based damage (meaning it scales), the pull and at least half the damage goes through magic immunity, his knockout provides ample time for you to pull off one or two (with refresher) blasts on the enemy team with little problem, and his aura (which is also spirit-borne, meaning you can just place it in the middle of the enemy team) kicks its damage up to new heights.
I think he's fun, really. His aura is amazing, but it has such a tiny range it can be tricky to pull off to good effect... But that does mean it can be skilled early without majorly pushing the lane.