I've been playing with the Pirate class fairly often recently, and one of the things that strike me - has has been mentioned before - is that it is slightly under-powered overall. Or maybe the Riftwalker I'm used to controlling is just overpowered.
Either way, the Pirate class is awesome. I particularly like the art and design and the way the character is made to look very Pirate-y and laid back.
Most skills are decent, such as the 'Pistol' and 'Swordplay' (Warrior) combo, and the 'Sea legs' (Warrior) skill does the job considering it doesn't require any mana. I absolutely LOVE the 'Summon Crackers' and 'Stun' skills, and think they're a very fun way of incorporating piratical animals and behaviour into combat situations.
Otherwise, 'Scurvy' quickly becomes less useful over time as its effect borders on insignificant the more one progresses through the levels. Likewise, skills that should be readily available such as 'Sneaky' and '1st Mate Aid' feel underwhelming as combat situations don't always fulfill the requirements for using said skills.
Also, the +70 enemy Crit chance for 'Shout' is quite risky, but that's part of the fun of being a pirate.
'LimeAid' works wonders, 'Cannon' is somewhat decent and 'Pirate Ghost' could benefit from a bigger ghost and a boost to damage. Overall, it's a pretty solid class for low-level players.