Right, this is an amazing game but could be so much better if there were not so many weird GUI issues, bugs and two odd choices.
GUI: Mixing the mouse and keyboard feels weird to start with and gets downright horrible later on with lots of birds, even the keyboard is objecting since pressing two keys at once often/always locks the vertical movement out and you slide awkwardly along the horizontal. Having to go to the bottom and then to each bird (especially pigeons) for each message (even when messages are grouped) is cute to start with but gets frustrating fast with lots of messages and birds... I spent more time giving messages than I did anything else in the game and paying attention to deadlines was not worth it beyond half-way through the game... make sure your birds are upgraded and just send them with the right size package plus don't take on the apothacary or the other short deadline patron... not worth the trouble because there is too much time just trying to get message to birds in the roost.
Bugs: Upgrades to birds cost nothing despite what it says. Birds taking twice as long as they should (occassionally but impactfully in the case of multi-parcel deliveries, especially with the queen given the hit to reputation is at least twenty well sent packages... plus the time it takes to do so given the decline in reputation over time. Looking at the bird seller screen when they leave the page makes it so you can't leave that page ever again... this is a HARD RESET BUG. Kernels seem to jump in price by ten times once you go into buying them individually (whatever the price marked) - I was within days tens of thousands in debt due to having run out of kernels... no the price being charged for kernels was not matched by what was being charged automatically. Going into debt doesn't end the game? It is not possible to leave debt though as the cost of kernels far outstrips your ability to make money.
Design choices: keyboard plus mouse. no save function. little to no information on the main stat in the game (reputation), it seems to be impacted by debt status, failed packages (by a huge degree) but not improved for delivering early or for larger deliveries (because four stork delivery a day ahead of time is entirely normal for a forge!?! Never mind four note deliveries over 1400kms on the same day - and that wasn't even a short deadline!?!?)
I have to say this feels a lot like a game that was always playtested from beginning to end (given the lack of saving this is even less surprise) and therefore the start of the game experience is very good and then the end of game experience is a terrible mishmash because little problems magnify to become big problems because the choice of "difficulty" curve was "all of them" (more packages, more reputations to maintain, more birds, less time (caused by a slow and inefficient UI) and way too much information that just can not be parsed in time... I would challenge you to create an automated bot to play this game to the end without having the same issues as human players (which given their speed suggests that the mechanics of the game themselves are the problem, not human skill).
Anyway, I have to say that this game starts out great and I could see it doing well in competitions where completion is not necessary but remember that fans will complete your games and may not stay fans if the game drops off in quality as one progresses through it... this is a real problem in clicker games, time blocking games and AAA games that playtest only the first few hours of their games because after that no refunds are possible.
All the best and keep on improving :)