Yeah, those things were all disappointments.
People had been fighting wars against Dragons for (hundreds of?) years and never tried shooting one?
The Greyscale thing was ridiculous. They lock up the books that have all the interesting and dangerous information in them, but this super dangerous obscure "cure" to a highly contageous plague is totally accessible, as are all the necessary ingredients, and the patient is in no way quarantined to prevent the infection from spreading? Plus the secret cure is the first thing anyone would try?
I guess I can see being outmaneuvered on the ocean, it's not like they had radar, but they did have a crow's nest

from which you'd be able to see another ship from many miles away. Night/dusk isn't really an excuse either. If you tried to sail a huge fleet of boats without any radar or anything in total darkness to "sneak up" on an opposing fleet, you'd end up crashing a bunch of them into each other, alerting the other fleet anyway, and sinking a bunch of your own vessels.
It has gone downhill a bit since it departed from the books, but it's still a very good show on the whole. Really there's nothing to be done about it. GRRM has taken forever to write the next one, and there's just no way they were going to shut the whole show down and wait.