I created a sneaky archer character (now lvl 46); yes, it's fun, but it gets sort of dull after a while. I maxed Archery to 100, and have since switched to one handed for the extra challenge and being able to keep leveling up (playing on Master difficulty).
A few days ago I created a pure Mage (Illusion + Destruction + Conjuration) after reading an excellet post by ResidentPianist, and I'm having a blast; tactics wise you have soo much to choose from; you can repeat a fight 3 times and each can be unique in how you approach it. But hey, that's the beauty of Skyrim, try one character and then another, and then another
It also pays not to have a single character doing ALL the quests, but instead having specialized ones (ie: my mage definitely won't be doing the Companion/DB/Thieves quests).