I didn't exactly hate it, i just thought it was really abrubt -- it just kinda ended.
Btw, the movie is SOO much different than the short story it's based on!

It leaves too many questions open. Like...

Did Melanie survive?

Did her and Michelle get together?

Is she evil?

What is causing the birds to attack? Is it the love birds? Melanie? Michalle mom in some thought of losing her son? A hormonal bird thing that makes them crazy? Or are the birds just staging an attack to claim what was one there's, the world? WHAT! For the love of god tell me!

There are too many holes at the end. You don't do a movie for 1 and a half hours just to leave the audience confused after watching it. Like they teach you in English class. Stories need to have a beginning, a middle, and an end

I heard that there was an alternate ending for the movie, but they censored it fearing that it was too depressing:

They get out of the house and drive to San Francisco, right?
And then, instead of it just ending there, they see that the whole Golden Gate Bridge is full of birds.

Are we talking the original ? If so , it was alright . The birds one and they just drove off away from they're house and that was it . I think a modern remake would be cool with alot of C.G.I. and humor in it , like in 8 legged freaks and Slither.

WARNING: IF YOU HAVEN'T SEEN IT... CONTAINS SPOILERS
I saw this pick a while ago, and couldn't answer before because the last time I had seen it was when I was a child (long time ago, trust me). Seeing the pick encouraged me to actually watch it last week, and I was very frustrated with the ending.
It's like... What? That's the end?
I definately agree that it left too many questions open.
I suspect that it may have had something to do with the lovebirds, because none of the attacks started until after their delivery.
As to the choice of vehicles, whether it was faster or not, I sure as heck wouldn't have taken a convertible. That roof could have been torn to shreds in moments. I'd like a bit more protection.
I also noticed that the pick-up truck looked like the one in the gas station fire, yet it was in the garage as a choice of vehicles. Did more than one person in such a small town have the same color and make of truck, or was this an error?
I haven't heard of an alternate ending, but what Nav noted doesn't sound implausible, and actually sounds like a better ending to me. I'm guessing that if there was an alternate like that, maybe they changed it to give more of a feeling of hope.