I respecced to mut in outlands and it was great. you take a lot less damage if you do it right because the mob spends half the fight stunned.
http://wowhead.com/?talent=fMecoEMsVzVoZV0ec0h some variant of this works very well for pve+pvp builds. i highly reccomend this if you want to pvp a lot 60-69 for honor. (i got enough for my medallion of the alliance before levelling). If you want to stay with it, then respec 20 points into the combat tree.
for solo pve,
cheap shot -> mutilate -> wait for ~70 energy -> kidney shot and get behind it -> double mutilate. if its not dead you have 4-5 CPs to finish it with.
you cant handle links as well with this, so be careful. i personally didnt use mut in hellfire, but as soon as i cleared the quests there i changed.
for 5mans
open with ambush -> mut -> Slice and Dice + attack trinkets, then spam mut while rotating 3-4 SnD with 3-4 Ruptures. Slice and dice is generally more important than rupture is. if your able to, try rotating targets as your poisons land. this is easier to do if you get improved poisons talent, but if your using deadly poison and getting a couple of ticks on multiple mobs it does amazing things for your DPS.
for pvp use a similar rotation, but remember you cant use blind or gouge because your using DoT poisons. in battle grounds i dont use the dot poisons, so i make use of blind and gouge for utility purposes or to use the time to get out of combat and get back into stealth.