I'm doing a destruction mage playthrough, and it's pretty fine so far. It's quite different from my usual warrior. So far I don't feel too weak, or bored yet. I'm playing with Lydia as my follower. I haven't used a follower in quite a while. It's a bit annoying at times, but it's different and kinda nice at same time. And I often conjure an atronach to be my second meat shield. I'm also using alchemy and enchanting. I'm Level 39 now on Adept. Flame spell is quite good in early game to level 20 or so and it was my main spell. It's effective and cost effective. It's easier to not get hit as a destruction mage than as a sneak archer, because you can move around freely while dealing damage. In this playthrough, being a mage means not using smithing or armor. I don't get damaged that often, so I don't get many chance to level up armor skills anyway. Giants can still one-hit kill me at level 30, but most of the time, they don't come close to touching me. I think people call this nature of mage glass cannon. I have 0 armor and I occasionally remember to cast stoneflesh. But it really doesn't matter. This playthrough has been a lot about not getting hit. I started to mix in firebolt and fireball as my mana pool got higher and cost went down. I collected magic related enchantments as the game went on. At some point in midgame, after level 25 or so, I started working seriously on leveling up enchanting to get to dual enchants. The process was pretty slow, but fairly smooth and generated a lot of cash. I used the cash to level up destruction with training. When I went to enchanting level 80, I crafted myself 90% + cost reduction gear. After that I've been using apprentice and adept level spells freely. I've also been using Bound Bow for sneak situation like in Falmer caves. Bound Bow has beautiful effects and it's a lot of fun to use, and it's quiet when capturing souls, which was strange but nice. I was worried about dragon encounters, and it was sometimes hard in the beginning, but fire dragons are weak to frost spells and frost dragons are weak to fire spells. Also, they seem to be vulnerable to impact effect. It's strange that you can stun-lock a dragon, when you can't do that with a Mammoth or a giant. I don't know if I will be able to stun-lock bigger dragons. I haven't met them yet. So, Level 39. Not feeling too weak or bored yet. Having fun. It's weird not having armor. It took a while to get used to that. But with crafting at 100 I'm about to be able to become seriously OP. I will need to be careful to keep the game interesting. Level 39: Magicka 310 Health 270 Stamina 100 Destruction 91 Speech 74 (lots of buying and selling with alchemy and enchanting) Restoration 43 Alteration 42 Conjuration 41 Enchanting 100 Alchemy 100 Smithing 46 (all from making iron daggers)
I was waiting for someone to post something like this

It′s pretty similiar to my character. Only Destruction I′ve gotten are the fire spells. They do highest damage from Destruction spells + Skyrim is cold place so many enemies weak against fire. Cold is often resisted.
Instead of mana cost decreased I use rise health enchantments. The extra HP helps since I have no magic resistance. Light Armor helps with warrior type enemies.
One handed Axe in right hand.
Max HP at about 430 and Mana 250.
If enemy doesn′t notice me, I cast Alteration with 60 armor rating, then blast 2 - 3 Fireballs (They cost much less mana to cast with 1 hand) and then I′m outta mana and the enemy is just close enough for me to make that last finishing blow. Axe has also fire damage and extra damage on targets in flames. (Which come from enchanting).
Perk trees I use are Destruction, Restoration, Alteration, Smithing, Enchanting, Alchemy, One - handed. Same difficulty.
Also playing first time, so few perks were wasted on Bow. Class is Wood elf... If that′s the one who starts with 50 extra magika?
Also, Stamina is only 130, I never use power attacks, never! - edited