I'm a high elf specializing in conjuration, smithing, enchantment and heavy armour, with most of my level up bonuses going into health.
It's a big success so far. I can take far more physical damage than a pure mage, and my +magicka armour and high elf abilities means I'm not noticably lacking for spellcasting. The only downside is that I'm reliant on Atronarchs for damage, but they seem to be holding up.
What I love is that this kind of character specialization would never have been possible in previous elder scrolls games. In Skyrim, while my character doesn't technically have a class he's still far less jack of all trades than anything I could ever make in Oblivion or Morrowind.