Nope, if you get further and further in the games, its about thinking using the enviroment, the way a tower crumbles and crashes into another while using the right bird.. its only frustrating cause its looks easy while it can be a brain cracker to solve a stage.  I used Terence, the big red bird, from time to sling above everything for him to roll back down a hill and destroying the pigs from the other side you would normally attack them.. if it was extremly frustrating, had cheap level design, faulty physics and boring birds the casuals would have dropped this IP a long time ago..

And i do want to say.. i was prepared not liking angry bird 2.. but still. i'm now at level 86.. I keep coming back to,, just one more level..

If you had bothered to check sources you'd have seen that:

a) It was Gamespot that said 1 billion

and b) that was as of may 9th 2012.....

http://www.gamespot.com/articles/angry-birds-hits-1-billion-downloads/1100-6375885/#ftag=YHF6738a5f

You missed the part where I said that it's more luck than skill. And that's what keeps them playing. Even if you suck you can advance eventually by pure luck.

Seriously though I played several hours of Angry Birds to know what I'm talking bout. I've had pigs rolling through the whole level and they didn't die even though they should (and they usually do); I've had wooden planks on pigs (with no space in between them) with big stones falling on them and neither did the planks break nor the pigs die. That's either bad physics or bad game design. In either way it's inconsistent enough for me to give up. I do come back but usually can't play more than 3 levels until I could throw my controller or phone against the wall.

All levels should be beatable in several ways, but they aren't. A lot of them have only one solution. You can't even choose what birds to pick next. So much for a puzzle game.

As I said, Star Wars isn't so bad. Angry Birds Trilogy is hell.
Also the sounds in this game are annoying as shit.

Its pretty clear that you kinda suck at Angry Birds, but thats not the games fault.. Millions of people are enjoying it..I'll bet your kid is better at it then you..  its probably one of the most popular games out there.. 6 years and still going strong..
 
Anyway not all pigs die from stones on them when the fall height and speed isn't high enough.. 
Levels ARE beatable in several ways.. but not at the start when they ease you into the game.. you said yourself you gave up.. and in 2 you can pick your birds (from a carddeck. you can pick from 3 birds..) Heck in 2 the levels buildingblocks are randomized..

I remember hearing the Angry Birds racing game beating Mario Kart total sales too :p

But smartphone games come and go really fast..

And now Rovio is making layoffs. I don't attribute this mostly to poor planning... just look at how big Angry Birds is.

Well most of the games are free...

These news make sooo damn happy, you have no idea!