I know the topic is a week old, but I want to reiterate what Feyras said.
I personally leveled combat until 50... 50-somethng? Combat had a lot of good going for it. Until I started getting some decent hit on my gear, it kept me from missing quite so much. I went swords, but I hardly ever saw the extra sword swing proc, so that seemed useless. Taking on multiple enemies was pretty easy, which was a plus before I got some nicer cooldowns like vanish and blind. It definitely felt a lot "sturdier" than Mutilate.
That said, mutilate at around level 50 was AWESOME. It's what I think of when I think of rogues. You sneak up and enemies are dead before they know it. But if you get a couple of enemies at once, you take a lot more damage, so it makes you pick your fights more.
Once I got to 60 or so, I started throwing points into random places outside of assassination. Relentless Strikes was awesome, and Opportunity was practically mandatory. Camouflage was useful for moving quicker and getting stealthed again quick; my fights typically lasted 5 seconds, and waiting 10 seconds for stealth to come back stinks. I'll probably end up going into combat for Precision (although I have a ton of hit rating already; 14.69%) and then into Dagger Spec.
All that said, I have amazing gear due to heirloom items, which as a new player you can't get. IF you can't get really good daggers (and you won't until at least 57-58), then combat is a safer route. When I hit 68 I started laughing like crazy, as my daggers jumped about 35 DPS each (from around 55 to almost 90). Without heirlooms you have to buy your way to that power jump (and the selection on the AH might be limited), and your results will still be poorer.
TL;DR: Combat until 50, then see what daggers you have and try out Mutilate. If you like it, take it. If not, forget it until you get Outland daggers. In fact, waiting until 57-58 gets you Opportunity and Relentless Strikes, both of which are awesome for Mutilate's build. Might as well wait!
Edit:
My rogue Edited, Sep 1st 2009 4:51pm by LockeColeMA