Keep in mind, this is all my own personal opinion. I reserve the right to be wrong about some things. And please post any insights that you have gained while playing with your wave 2 ships. But here is what I have found so far:
With wave 1, the top Rebel squad was a 4 ship build, with usually 1 top pilot (often named Wedge), and 3 level 2 pilots. For the Imperials, the top squads were 6+ TIE swarms (yes, I know your 4 ship TIE Advanced build is undefeated, but I'm speaking in general terms), and there were many varieties of successful TIE swarms.
From what I've seen on the boards, Rebel squads are tending to go in 2 directions; 3 ship X-wing builds, with high pilot skills and lots of upgrades, or 4 ship builds with A-wings with missiles. Another option is 3 ship builds with a YT, which may prove to be more effective than people think. Imperial squads are tending towards 5 ship builds, with 2 interceptors being the norm. Both factions are now getting away from lots of lower pilot skills and moving towards fewer ship builds with higher pilot skills. From what I've seen, this is where the game is moving. Not that the old squads are necessarily bad now, but these more streamlined squads are going to fare better in tournaments. I also think that more games will end before time gets called due to the lower ship counts on the board, especially in Imp vs Imp games.
With Wave 2, we now have the Boost action, which does change the game. Now a ship that was in your line of fire can boost out of it by taking the boost action. So now you need to have multiple firing acs covered, so that you can still get an attack against a ship that has boosted out of one of your ships firing arcs. Or more importantly, deter him from boosting, and make him take another, more defensive action, like focus instead. I think this is an important point that people haven't really considered as of yet, which is understandable due to the relatively few wave 2 ships that are out there. As an Imperial player, covering multiple firing arcs is difficult, because it takes away squad cohesion in favor of spreading out to cover areas. For Rebel players, the YT will solve this problem quite easily by itself.
We also now have Stealth Device. The good thing about Stealth device is that it's cheap, 3 points for an extra agility die, which can be added to any ship. The bad thing about Stealth Device is it's expensive, it only comes with the $30 Firespray, so getting 5 or more will cost you. You do get 2 of them with the Firespray, which is nice, but still, they will be pricey to obtain. Stealth Device now makes ships with a 3 agility into a 4 agility. I believe this changes the game as well, because having 2 attack dice just isn't going to cut it against 4 or more defense dice (add Range 3 through an obstacle, and you're rolling 6 defense dice, which has happened in games I've played.) You will need a ship with at least 3 attack dice to strip away Stealth device, so that your other ships with 2 attack dice can have a better chance of hitting once the Stealth Device is gone. I predict nearly every squad will have at least 1 ship with Stealth Device. My Dark Curse with Stealth Device hasn't taken a hit yet in the 5 games I've played with him.
We also now have Assault Missiles. I know there was much ballyhoo when this was announced, but I think clearer heads have prevailed. I have used Assault Missiles twice, and have failed to hit both times. I don't think this will be quite as game-changing as people originally thought. It seems that Homing Missiles are a better choice due to not having to spend your target lock to use them.
Then we have the large ships. No, there will not be anything produced that will be bigger than the YT-1300 and the Firespray, so please stop calling them medium ships. I think even if there is an Imperial shuttle produced, that it will have the same base size as the YT/Firespray. In my own experience, I haven't been able to successfully play the Firespray effectively. I've tried, believe me, but the most effective use of the Firespray is through its front firing arc at range 2-3, which usually will only happen once or maybe twice per game before it gets destroyed. To me, I'd rather use the points on other things, as the smaller ships fit my playstyle better. The YT has a 360 firing arc, which makes it a better ship than the firespray, IMO. There are many times when a firespray won't have an attack, but the YT will, and that's a big difference, especially at Range 1. The YT pilot's abilities are more squad-based, specifically Lando and Chewie with Draw Their Fire, than the Firespray pilots. And to me, this game is more about squad cohesion than one big, beefy attacker.
Oh, and I can't talk about Wave 2 without complaining about the A-wing. Eight green maneuvers is just plain broken. The ship only has 16 maneuvers, and having half of them be green is just plain wrong. A TIE fighter, TIE Advanced, Xwing, YT, and Firespray all have 4, Ywing only has 2. The Interceptor has 7, which I'm fine with reducing if we're going to reduce the Awing's. IMO, both the Awing and Interceptor should have 5 green maneuvers for balance. I'd say 2 straight, 2 banks, 3 straight, and 4 straight should be it for both the Awing and Interceptor for green maneuvers, but I didn't design this game.
That's about all I can think of for now. If I think of more I'll post them.