PvE is pretty imbalanced
The first thing you'll need to do when playing a character on patch 4.0.1 is to choose a new talent specialization. Each spec has its own flavor, determined by the rotation-changing talents in the tree and the passive mastery bonuses attributed to each. Subtlety's damage is actually in a really good place right now, while combat rogues are masters of any multi-mob encounter. Assassination rogues swap their rotation when their target is below 35 percent life, which adds some variety to the spec.
Once you've picked a spec, remember that the new glyph system should be active, and so you'll want to visit a friendly scribe and have him craft you the proper prime, major and minor glyphs. I'd suggest trying out some of the fun glyphs rather than focusing on a pure min-max goal. Class imbalances and bugs are going to shape your DPS by a far larger margin than putting new gems into your gear or swapping between two glyphs that provide nearly identical amounts of damage.
For all of you leveling rogues, be sure to go and pick up any of the new moves that are available for you. Blizzard dramatically changed the path of skill learning as you level, and so there are likely to be new goodies available. There will even be spells available for level 80 rogues. We won't have access to any of our newer spells like Smoke Bomb or Redirect, since we can't level past level 80, but Recuperate alone is worth the trip to the trainer
One other thing: Your gear is going to look a bit funny. Not the models themselves, but the actual stat values will be different from what you remember. Armor penetration has been replaced by critical strike rating in most places, and attack power has been rolled up into agility on much of your gear as well. I know it will be painful for us to lose all of that precious ArP, but hopefully it will result in a more balanced game in the future. It's also nice to have a ton of crit chance, especially since resilience no longer reduces a player's chance to be crit. It only reduces the critical damage taken, so rogues with a ton of crit will still be fairly powerful against other players.
Try out the new Vanish
Go start a fight. Find some unsuspecting enemy player and attack. Let him have his way with you for a little bit, as he applies his DoTs and bleeds. Then, when you're ready to make your move, use Vanish. Watch as your enemy loses sight of you. Observe as the DoTs tick, dealing damage but yet not revealing you. As you wait in the shadows for your guaranteed 3-second window, realize that you are living in the future. After years of waiting, sometimes patiently, we finally have a working form of Vanish that will satisfy even the most potent skeptics.
PvP is a mixed bag
Speaking of getting into a fight, there are a few classes you'll want to watch out for on the beta. Our old rivals, the feral druids, are actually pretty weak right now due to their low damage output. Feel free to assault any kitties or bears you see without fear of being Mangled to death. Beast mastery hunters, on the other hand, are incredibly powerful. Their Kill Command ability strikes fear into the hearts of all, and you should run if you happen to encounter one. As far as trying to gank any other class, you're really rolling the dice with your life. You may happen upon a weak spec that falls quickly, or you might try to tackle a powerful build that needs some serious retuning. Either way, I'd suggest just attacking everything you can see. You've got guaranteed Vanish now -- what could possibly go wrong?
Check back every Wednesday for the latest strategies in Encrypted Text! Get ready for Icecrown Citadel with our rogue guide, part 1, part 2 (Plagueworks), part 3 (Crimson Halls) and part 4 (Frostwing Halls). Just hit 80 and need information? Try Combat 101 or Mutilate 101.