I tried mercenary work. It didn't suit me.
All that said, Skyrim is a hella fun, until you do everything, then it gets hella boring.
[SPOILERS BELOW]
After you beat the main quest, become the leader of pretty much every organization in the game, and get 100 smithing, enchanting, and alchemy, there's really nothing left to do. You make yourself a godly set of gear that makes your favorite spells free to cast, hit armor cap and resist caps so you're basically invincible, and you don't even need to level up anymore...Technically there's "infinite quests" thanks to this "radiant system" so you're supposed to be able to keep playing for-ev-uhr, but all the radiant quests are the infamous "gather 8 bear pelts, then go kill 5 bandits, then..." type.
That's not to say I regret buying skyrim. After owning it for only a month I clocked like 200 hours on it because it was so addicting. And once they release the construction kit I'm sure I'll have plenty of user-made content to delve into. I'm just saying that the "omigod this is like a single-player WoW" feeling does die out eventually.