Vehicle damage was better in IV - Again I disagree. It was more convenient in that you could destroy cop cars much more easily in a chase, but then it also meant you could die more quickly too. It felt like only a few accidents or bullets and you car was done. Going back to my first point, I found this very frustrating. I would spend all thise extra time looking for a sport or super, only to have a few accidents and lose my car. Now I have to go out and find ANOTHER sport or super because I'm not about to drive around some POS SUV or sedan. And the way damage is done in V is much better than IV. In IV the car just took damage and that was it. In V you could lose a tire, blow yours trans or your suspension, and they can still be destroyed (I've had it happen). It makes damage much more dynamic. Lose a tire and it becomes more difficult to steer and keep control. Blow the trans and now you can't accelerate and get stuck at one speed. I even on time had the suspension destroyed and I could literally not make turns anymore. Car would just drive forward (and to the left because I also had no tire). It definitely makes running from the cops more challenging WITHOUT becoming a tedious chore. Not to mention, it makes chases more fun because you can shoot out someones tires and keep on them with ease.
I agree that the damage in V is way better than IV was in the way that wheels, bumpers, and other parts can come off. But the amount of things you have to do to get it damaged is ridiculous. It makes it more fun and interesting trying to run from the cops or getting from point a to point b without completely demolishing your car when it's easier to damage.
Air Control - I love this feature in V. One thing that bugged me in IV was that you lost complete control in the air. Yea, it's more realistic but sometimes I find myself going airborne over the shortest hills, or hitting some random polygon that launches me a few feet up. Now I'm at the mercy of the physics engine. Especially annoying doing stunt jumps, as if you missed the jump by a micron you would go all crazy in the air. Throw in the way damage worked in IV and it just meant I either died or lost my precious super because of a minor miscalculation. Also, the vehicle flipping in V is great. If I somehow managed to crash my precious super, or miss that stunt jump by a micron and still land upside down, I can at least salvage my vehicle, repair, and try again. If I spent a ton of time and money finding and upgrading a fun car I don't want to lose it nilly willy to some random pixelated water bottle that threw my jump all out of whack.
Have you literally not played GTA IV at all? If you did you would know you can control your car in mid air, and it's better than the way it's controlled on GTA V. The only reason the Air Control on V is better is due to the fact when you start turning the yaw of the vehicle on it's axis the camera doesn't spin like on IV. But yeah, you have complete control of your car while in air on GTA IV as well, and it was also on GTA San Andreas. I guess you were just too blind to notice it.
Flying - Choppers and planes are definitely more difficult to drive in V, but I found that the flying stat really makes a huge difference. Flying as Trevor, who naturally has 4 bars for flying IIRC, is much MUCH easier than flying as Franklin, who starts at a pitiful 1 bar. It's like night and day. But even playing as Trevor it's a bit trickier to come to a full stop and just hover. In IV it felt better, so this is probably the one thing I felt R* messed up. I mean, I can understand my troubles with Franklin, but Trevor (who now has full bar) should be able to easily stop on a floating dime and not be all tipsy. However it's not drastic, so I can deal with it.
I agree that IV felt better flying choppers too, because now on GTA V when you try to fly the buzzard, for example, it's almost impossible now to aim with machine guns and shoot people on the ground or in a vehicle. I can usually hit most things with them, but it's much more of a pain now due to the headwinds and other things affecting the chopper. I've been piloting on IV since 2009 and I can hit almost anything with my Buzzard or Annihilator on IV, but now even though I can still aim decently with V's chopper, it will be impossible for people who just started on V to master the machine gun on the heli and get good at it. I really don't see why they made driving much easier and heli flying so odd and difficult. Also another thing with the heli is I don't think the propellers can really break unless the heli blows up, and the back tail doesn't seem to break either. I'm not sure yet if it can, but what I've tried so far neither have came off in flight.
Motorcycles - I hated motorcycles in IV. One of the main reasons I didn't purchase the Lost and Damned DLC. It was just the frustration of steering combined with the fragility of the vehicle, and add in the fact that you have no air control and motorcycles become the most pain in the ass vehicle to drive in IV. Again, you could argue it's more challenging, but there's a difference between a challenge and a frustration. Challenge is fun, frustration is not. A challenge is stuff like landing on a moving train with a motorcycle (like the one mission you do) or racing around the city at high speeds STILL with a huge risk of crashing catastrophically if you don't dodge every car and light pole in your way. Frustration is slowing down significantly over speed bumps, wiping out and taking damage/dying when trying to make a not-so-sharp turn, fishtailing on a straight away at high speed all because you didn't want to hit the SUV you were trying to pass.
How was it frustrating? It really isn't. I could drive just fine at high speeds and hitting ramps, jumps, or bumps with a motorcycle was much more enjoyable. Also doing flips were way more better and fun too. Now on V when doing a flip with any bike or using air control in a car, it takes forever for the vehicle to do a flip. If they're upright they can lean forward and backward pretty fast, but the moment when you go upside down, it takes an hour to make it do a flip. I don't get why they did that. And again, Air Control was in GTA IV.