A few things jump out to me about the Swashbuckler. These things I feel really define it's class as unique, so I'd like to address them.
Dodging Panache: reasonable to me. I get to use CHA for something that most other classes don't, and it's temporary not constant. It fits thematically, and technically. I love it.
Opportune Parry and Riposte: Sounds good! Great even. A way for me to get in free-attacks fits very well. Not guaranteed but nonetheless very potentially helpful. My DPS just got a boost and in addition the fact that I'm a "mobile fighter" definitely promotes the importance of abilities to negate damage from attacks.
Precise Strike: I like it. I feel it scales well, which is something I was really looking for with this class (how well it scaled into later levels).
I was disappointed to learn it didn't multiply on critical hits (melee types who use 1 weapon in 1 hand seem like they need crits to compare to their TWF or 2Handed counter parts imo).
...But then grew slightly more okay with given the option to spend panache to double it. Seemed reasonable. But then I saw you could only use this as a swift action.
...So here's my first hangup: I can't "double precise strike" when I make an opportune parry? Perhaps in initial playtesting that was OP... but thus far Precise Strike is my primary damage source. And the fact you could potentially use it on your opponents turn (something much rarer for TWF and 2handed fighters) struck me as an awesome balancing act. As well as the first real unique thing this class could bring (outside of Duelist).
I have Bonus Damage tied to my level (class loyalty, gives me a reason to stay. Fighter, Ranger, Barbarian, doesn't get that.).
I have CHA giving me AC, Panache, and Charmed Life. (Excellent, I can level that at my leisure with magical items, ability point buffs etc).
DEX then will be my second stat...which I'm a little disappointed there wasn't more of. No class ability actually uses DEX. Mind you--you kind of are expected to be using it regardless. I just mean no Panache stuff utilizes your DEX mod. Just a bit disappointed at the lack of to-hit bonus or damage bonus.
So here's what it boils down to for me when I compare it:
TWF gets lots of attacks typically crit focused. Huge Damage potential.
2-handed gets very powerful attacks, and makes up for the fewer number of attacks with adding on huge (1.5 or 2x STR, and power attack) bonuses. Reliable damage.
The Swashbuckler should find their niche in opportune attacks with some clever damage. Trading some of that damage for AC and Utility is reasonable... but this is still a melee fighter class, and should have some way to make up the damage discrepancy between itself and the other fighting builds.
I'd like to see more done for increasing their Offense or their Defense. Right now you sort of get both naturally without making many choices.
I feel where they stand in terms of Defense and Damage (when compared to their Fighting class cousins) isn't exactly ideal. Our CHA bonus won't keep that Dragon from hitting us with it's +30 to attack.
Our Level in bonus damage won't do much when we're only landing 2-3 attacks at higher levels. Especially when a lot of damage at that point comes in the form of Criticals.
Just my 2gp
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tl;dr
I like the idea of "strategic, opportune, daring fighter!" The type who was dancing in and out, taking advantages of the opponent through clever maneuvers.
So, I'm more than disappointed that Precise Strike and Opportune Parry and Riposte can't be used in conjunction.
Those seem like the bread and butter of the class. I want my bread with my butter.