I watched the Colombian version (Betty La Fea), I think it was the original one. That version was really nice because all the characters had a good part and they all had distinct personalities that bounced off from each other when they interacted. The Betty was also socially awkward, a real ugly duckling so to speak, but she was very nice and timid but very very smart. She also had disciplinarian parents and she was very conservative - so I guess that's why she was more quiet and timid in the Colombian version. Part of the charm of the show is how Betty's character accepts "falling in love" even though at the back of her mind, she knew she was bound to get played (since she was smart and she was timid to the point of having low self esteem) but when she gets her heart broken, she rises up and decides to come out of her shell and boom. everyone is surprised at how beautiful she truly was.
I suppose this version is more loosely based on the American version (though I haven't seen that one). That's why the Betty is more upbeat. I would have wanted to see a Thai treatment of the Colombian version, I thought it would have had a closer connection to the culture, etc.