Was playing last night and this morning. It's got Star Marine, which was kind of fun. The flight dynamics have changed and there's been ship/weapon balancing. It's taking a little while to get use to using afterburner instead of cruise, but I think I'm finally getting accustomed to it. I can't say that it's more stable than 2.5, because I didn't have any issues with that one either.
A few things I noticed... I get fewer crashes when I use the hangar to enter game modes. Servers have been more laggy/problematic than I've experienced in the past. (can't spawn a ship, etc intermittently). Freelancer doesn't remain stationary after EVA. there is a lot more stuff to find in Yela and the pirates around the ICC missions seem a little harder to kill, but that could just be me getting use to the new flight characteristics. EVA'd in and around Grim Hex for more than an hour this morning, but after about 3 hrs of gameplay, the game crashed. I wasn't disappointed, but it was a little laggy at times and Grim Hex dropped fps pretty low when I was inside.