Destruction magic will be the magician's fallback. It's split into three schools of flame, frost and shock. Thankfully, getting more advanced spells isn't just a matter of just getting a bigger fireball. It's a matter of widening your arsenal. The flame-throwing palms you start with are useful, but the Fire Rune traps and explosive Fireballs give you a chance to experiment with tactics.
They also allow you to kill your allies - while I noticed my AI-controlled friends getting temporarily knocked down by enemies, I only ever noticed them permanently dying from my own splash damage. Other schools shouldn't be overlooked - Conjuration lets you raise your victims to fight alongside you, and summon spectral wolves and atronarchs. Restoration is essential, unless you want to rely on potions and regeneration. The system is impressively open, with grades of ability more of a guideline than a requirement - a novice mage can cast a fireball two ranks his senior, but without the appropriate perks the magicka cost will be crippling, and your lower skill rating will make the damage less impressive. Self-improvement has just the right balance of slow-creeping and bold jumps.
Beautifully, the decision on how you're going to specialise isn't as crucial as it was in Oblivion, for two reasons. First, your overall level is calculated from all your 18 skills, not just the class-specific ones. Second, the world doesn't level up with you, so you can always get stronger and go back. Bethesda has created a flexible, constant and immensely satisfying system of levelling. Oblivion's levelling was designed to make you doubt your actions and fear sleep and levelling up - you felt like the mistakes you made in the over-wrought character creation dungeon would haunt you throughout the game. By tearing out classes and world-levelling, Skyrim makes improving yourself an unfettered pleasure.
I naturally found myself using a varied loadout. I'd start most fights with a sneaky bow attack, resorting to dual-wielding destruction magic - flame, frost or shock, as appropriate - as they got closer. When mana ran out, I'd tap out to heal and sword, using mana as it recovered to keep my alive. Three tactics, boosting six skills. As you find new enemies, like the half-blind Falmer, and the Dwemer machines, you'll be forced to find new tactics. Melee combat isn't as "connected" as has been implied - running away will often result in your death from a blow that was a clear foot away. But Skyrim shouldn't try to be Bayonetta. It all works brilliantly. Just make sure you're well-saved - in the world map, the game doesn't auto-save nearly often enough.
Despite what the big number 10 below implies, the game isn't perfect. The world map may be seamless and loading-screen free, but moving indoors and across the map, the load times are long, so install it if you can. The world itself feels oppressively you-centric, with everyone stopping to say their line of speech at you, to the point of maniacal repetition. The sound mixing can be annoying, with an important conversation drowned out by a bard singing a song in the next room. And would it have hurt to write more songs? Sixty hours in, and "The Age of Aggression" has really got me aching to throttle some bards.
The menu system is elegant in its overview, but imperfect in its detail. You can allocate spells and weapons as favourites, putting them into a menu that appears when you tap up or down on the D-Pad. That's fine, avoiding the need for full-menu foraging mid-battle - it needs maintenance as your arsenal grows, but sifting through all the new shit you can do is part of the fun. However, you can also create left and right shortcuts. This doesn't really work, because the combat is designed around a two-handed battle system, and these left-right shortcuts can only be allocated to a single item. Fine for a two-handed weapon, but not for sword-shield and fire-heal combos.