Ice/Steel has some major weaknesses, but it could be a cool concept (no pun intended). I'm envisioning a pokemon based on refrigeration devices. It may seem stupid, but it could be interesting -- kinda like a Magnezone. Maybe it could be an alternate evo for Magneton.
The refrigeration device theme could be used as a justification for a Heatproof ability (think "insulation") or a new ability with outright fire immunity. That would help remove one of those 4x weaknesses. Having 2 common 4x weaknesses is an insurmountable limitation for any pokemon to be used competitively. Just look at Rhyperior. Even with all that power and an ability geared to limit the weaknesses -- it just doesn't work well. I love the potential of Ice/Steel, but only if we minimize the 4x weaknesses. No "Solid Steel" ability or the like. In competitive play, a 3x weakness is just as bad as a 4x weakness.