'm a fairly new Human Rogue at lvl 28 that likes to do PvE solos and group grinding and quests. I want to respec a little and I'm thinking of the following build of 30/10/21. Does anyone have any suggestions for improvement?

Assassination (30)

Eviscerate 3/3
Malice 5/5
Ruthlessness 3/3
Lethality 5/5
Improved Poisons 4/5
Cold Blood 1/1
Improved Kidney Shot 3/3
Quick Recovery 1/3
Seal Fate 5/5

Combat (10)

Sinister Strike 2/2
Lightening Reflexes 3/5
Precision 5/5

Subtlety (21)

Master of Deception 3/5
Opportunity 2/5
Dirty Tricks 2/2
Camouflage 5/5
Initiative 2/3
Ghostly Strike 1/1
Improved Ambush 3/3
Setup 2/3
Preparation 1/1

Specifically, is it better to go with Murder 2/2 and Improved Backstab 2/3 instead of Improved Poisons?  Also, is it better to skip Opportunity and put the points in MoD, Elusiveness or Initiative or Setup? Thanks for any assistance.

Seal fate/premed is best spec imo. You get good opening shots, hemo for combo points spamming, preparation and a good stealth ability from the sub tree. Then from the assassin tree you get imp. backstab and lethality for big backstab crits and cold blood which is guaranteed crits which can also be reset with preparation and seal fate for mad combo points building. The last few points can be used in setup initiative and premeditation. You'll be a very versatile rogue especially if you carry dagger sword combo with an addon for auto-switching your weapons after ambush to put your sword in main hand for mobs or just keep your dagger in main-hand for pvp and just spam backstab for mad crits and combo point generation. For pvp if you take up iniative with improved ambush gives you around a 65% chance to open up with a ambush crit which will give you 2-3 combo points then around a 50% chance to crit ambush which gives you 5 combo points in about 4-5 seconds then hit cold blood and drop a guaranteed critical eviscerate. You'll just dominate all your oponents. Remember all your crits give you double combo points, so this spec is also great for building up quick combo points to drop armour ignore against heavy armour wearers or quick points for high damage output against clothies and leather wearers. All around a very high dps/high versatility spec. You lose too much effectiveness in your main tree or secondary tree when you try to spread across all 4 (30/0/31)

back stab +mutilate are dead.. forever resilance killed the assanation tree ur better off going up the old (12/0/49) tree hemro build man

To Rapids,So you think the extra 2% is useless?Think again my friend the scale you used is so small its apalling.Lets take for instance the raiding rogue,in Heroic bot I can put out 1 million damage easy.So that would be an added 20,000Damage for having the +2%damage.Any raiding rogue who doesnt have the points in this talent that you call "the most useless ever"is going to be lacking A LOT of Dps.Also you list something to not put points in but you fail to mention what the points would be better spent on.Obviously you need to learn your class better and learn math before you tell all the newer rogues here that this is the "most useless ever" when to a raiding rogue this is one of the most beneficial for the (20,41,0)Combat spec.

People,its 2% per hit,not an overall..need i say more
thats still 2% more dmg per hit than any other person.

per hit / overall.... what is the difference ?

2% per hit isn't big huh? reroll dude, reroll. good rogues swing fast, and hit often. do you have any clue how many times a rogue hits a target in fight against a mob? now mutilpy that by the number of mobs he fights. if you're rading, add boss fights in there as well. that's like a rogue saying slice and dice is useless. congrats. you're an idiot. anyone use recount? check out what is at the top of your damage meter for your toon (i.e. what got you up to that 660dps or whatever)*drum roll*.....MELEE!! not sinister strike, not hemo, not ambush. MELEE. if its not, can we say wtf, over?