Yeah, it is more than just a neat thing. I've talked to a few people that have tried out shaman and from what they are saying in the hands of a skilled player it is quite likely THE single most powerful class feature in the game.
Consider: The SC is immune to anything except direct damage. You cannot put ANY effects on it at all. It takes no damage from zones or blasts and bursts, isn't impeded by terrain at all, can effectively teleport to most areas of any battlefield, etc.
Here are some interesting things it can do that a character cannot. It can simply block an area of 1 square, denying ANY access to that square to the enemy. They cannot push it aside or otherwise move it or do anything to get past it except pop it. Even that doesn't work well because the shaman can simply set his minor action summon SC to trigger on the SC being popped! So it is kind of the ultimate wall. It is a small wall, but if you want to hold a doorway, it is a REALLY tough thing to get past.
It can largely negate a controller or artillery monster's defending skirmisher/soldier/brute/minion front line. The SC simply pops into existence behind the line and goes for the back rank monster. Many times at lower heroic the monsters really have VERY little chance of even popping the thing, and thus the shaman can hammer on them at very little risk to himself.
Quite often the shaman can arrange it so that the SC can see the target but the target cannot see the shaman. This is actually pretty easy to do in a pretty wide variety of terrain.
When faced with a single monster the SC really IS the ultimate meatwall. Aside from maneuvering the shaman into a corner or somehow putting a condition on him that stops his movement completely it is nigh on impossible to get past the SC. Even if you pop it, that eats the monster's attack for the round and if it pops and moves up it will take an OA, then the shaman will just shift back, pop in a new SC, and use his standard to either attack or open the range another square or two or however many he feels like.
Like I say, I talked to a couple of good DMs and both of them were really seriously beginning to wonder if the shaman is a balanced class at all. Maybe that was a bit of an overreaction, but the class sure does seem to offer some amazing flexibility. Consider, this is one of the few, if not possibly the only, class that one might seriously building an entire party from. No doubt such a party couldn't handle EVERY possible thing that could be thrown at it and you could devise some tactics that would beat it handily, but I think it would stand a really good chance of shining in any arbitrary encounter.
