Cards like Ice Cage and Excomunicate are tempo cards. They put you ahead in a race they are very good and usefull, but you can't consider them solid removal. They don't solve creatrues they solve timing. It is better to think of Ice Cage in the same way you think about Sleep, rather than thinking about it as a pacifism.

Ice cage is good because It stops early aggressive threats when you don't have an answer, unless they are playing 3 Unholy str or what Charlie said. I like it but don't value it super high. When you draft in Boise at a store it will be drafted like a Narcolepsy though

I think the consensus, or part of it anyways, is that most of the cards that answer it are maindeck/always-play cards. Some answers are better than others for it, but you know when you have to burn down the cage with a card you don't want to use on it, like Mighty Leap or Giant Growth, or even Shiv's Embrace if they are tapped a bit. The other options are instants and you can play around the person who cast Ice Cage.
In sealed you only play it if your blue says you want that color anyways, but it doesn't turn you towards that color on its own.

It's a fine enough card that in most situations it will range from good to great. You named the obvious cards that will take care of it, but in most situations its really good. And I agree with Charlie in that it is better in draft than in sealed.

I don't hate it. I've lost to it a few times, but I always have outs to it in my deck that I could draw that would make it horrible. Any equipment shuts it down. Blinding Mage is my usual answer to it, but he can be put in the cage so he isn't that big a deal. I'm going to say its better in draft because there is less likely to be equipment in the deck than in six random packs (any equipment is almost an auto-include in M11 sealed) and the format should be faster. In sealed, I'd only play it if I was short on removal.