[quote=@Jerkchicken]
Is it even that much of a difference? What with PF being basically more of the same with some "improvements" and even more classes to cater to the fanbase that was put off by 4e's approach.
[/quote]
To qualify to become a shadowdancer, a character must fulfill all the following criteria.
Feats: Combat Reflexes, Dodge, Mobility.
Skills: Stealth 5 ranks*, Perform (dance) 2 ranks.
3 feats and feats are available at 1st, 3rd, 5th character level. Ranks are available at 1/level and a +3 bonus for being a class skill  instead of 4 ranks at level 1 or 2 for cross class. So RAW one can meet the requirements by 5th in any class.

But these are guidelines more than hard rules and I use them for myself more than against the DM so that I don't run amok doing anything I like and just yelling 'pirate' like a landbound jack sparrow. He has strengths and weaknesses, skills he has and skills he lacks. Claiming to have open/close and lesser darkness 3/day prevents me the player from spamming or getting too 'creative' if stuck in a spot.