Hello Andy,
First I'll say the most easy fix. I've noticed that during the start up sync it seems to pause the rest of the app in the background while the spinner loads and displays. It definitely takes longer than a second for all that to happen and I find myself tapping the first pending flight entry (the one I just completed and want to update) multiple times and waiting until it will allow me to access it.
I think this is simply the device bringing the app out of suspended state. I don't know if Apple is doing this but in the past what devs have done is take a "picture" of the last screen and that is shown at next startup to make it look like it's starting faster. Apple may be doing this so you're seeing the app in the last "state" while it's actually reloading in device memory. I do have a task to try and make that spinner show up immediately, I tried fiddling with it in 1.0.5 and was never able to get it but I'm not giving up. Just know that if you have Sync on Start to wait for the spinner to appear which means you can start using the app as it is resumed.
The one thing that is annoying me the most is the auto calculate "calculator" icon. It seems that since 1.0.5 it has gotten harder to tap.
It sure has for iPhone 4 users. I changed the image for Retina display compatibility and it reduced the tappable area because I did a trick for version 3.x to make the tappable area larger. I *will* have it fixed in 1.0.6 as I just need to do the same trick for the retina 4 (iPhone 4) system. It was never an issue in testing but you're the second person to mention it and I had a hunch it may be an issue. However, there is one thing to know about "tapping" when it comes to iPhone apps. In most apps it's not where you press "down" but instead where you release. Apple has a neat system for gestures (swipes) and also with this is it allows you to avoid inadvertent taps by sliding your finger off the tappable area if you touch something by accident. With that said, when tapping the calculator image it's important where you release your finger. So if you tap, slide left and then release, you'll miss the target. I suggest trying to release "up" on the left edge of the calc button for now, iPhone 3G/3GS and iPod users do not have this issue as much due to the trick in place.
These next two kindof go hand in hand. I know this won't affect the people that don't use OOOI but what exactly is the difference between the date at the top of the entry screen and the date in the OOOI area?
I see your point and you'll notice the OUT date/time initializes based off of your Flight Date. I'll have to think about this and see what others have for feedback. I could also add in a warning prompt that OUT is not the same as Flight Date and allow you to leave it, i.e. not be an error. There is probably a situation where you could have a flight date different from OUT. I remember in the Air Force something along this line when we night flew. The Flight Date was the calendar day such as Thursday yet we took of on Friday at 1 AM. Strange, but situations like this arise so I have to be careful about thinking OUT is going to be the same as Flight Date.
And finally we come to the picker wheel…again
This is the device, not the app, i.e. the native picker on the iPhone. It could happen to any use of this spinning UI that the iPhone has. You may have mentioned this but the trick is to tap the target date or time and the spinning wheel will change to align with that. For example, you may flick to spin the wheel and then when you see the exact time, don't try to touch/drag to align it with the result, instead just tap the result and the wheel will change to the tapped target date or time.
Hope some of this will help you overcome the items you raised. Thanks for the compliments. It will continue to get better, sales continue to amaze me and the bug reports are mostly educational problems, i.e. how to do something vs. problems now, which is great. Hopefully Apple can fix this suspended app situation, it's even affecting iPhone 4's now which I didn't think it would, I think they need to do like Android does which is kill older apps in suspended state as newer ones are used. Windows Mobile did the same thing.