While Sion is more fun to play, it has come at a cost of him being ineffective in practice.

How can this be? How can something be so fun, yet so bad to play at the same time?

The answer really is just a numbers tuning. Riot got the part right on how Sion's gameplay is, what he does, how he does it, the sounds, his theme. They got all that right. But he's SEVERELY underpowered from a numbers tuning standpoint.

1). He's too fragile. He'll probably still be too fragile even after the buffs, as missing that much HP is pretty bad. Apparently CertainlyT said that during testing that the feedback he was getting was Sion was too hard to kill. And I have to ask, is that a bad thing? Sion is a champion that gets dicked over by ANY kind of mobility. I don't think it's a problem if this guy is hard to kill. And there's plenty of answers for combating HP stacking. I have to question the validity of Riots Gameplay Testers.

2). He doesn't do enough damage. This is a big issue. His ultimate and Q Damage are just laughable. These abilities probably should be doing much more base damage OR AD Ratio than they currently have on him (Q needs much more base damage, R needs much more AD Ratio, and change it from Bonus to Total AD). His damage is high on his Q for the first couple of levels, i'd say up until level 9. Then he just tapers off badly. You don't really build AD on the guy because you can't afford to. He's too fragile! (see point 1).

3). Speed boost from his passive should not taper off, and should last longer. CC abilities do exist, and they are the bane of Sion.