I actually liked that they gave Hawkeye a little more screen time, especially since he doesn't have his own movie.

I do agree with you that Thor's cave swimming needed a little more explanation. I also don't really understand how The Vision was created. You take some of Ultron add some Jarvis, Zap it with lightning, and you get a red skinned dude with internet powers? I don't get it.

I'm also getting tired of every single one of these movies ending with the good guys killing a million bad guys. Maybe it would have worked if the robots were actually doing any damage and were wearing down the good guys. It would have been nice to have a the drama of "I don't know how long we can hold out.... Instead the Avengers were totally invincible and the robots were getting torn apart like tissue paper.

I did like that for a little while Ultron and his allies seemed very formidable. I liked the Hulk vs Iron Man fight. The shear violence of the Hulk was scary and effective.

There are a couple other plot holes that give me pause. They infiltrated the Hydra base at the beginning, but then they just left all of the robot and techhnology there? They only wanted the staff? What the heck? Also how did the city-lifting-jets / astroid forcefield suddenly show up? When did Ultron have time to make those? Or were they left behind by hydra? I don't get it.

Whatever. As you said, it was still fun. It was worth the $8 I spent to see it.