Predictive texting on the Samsung is far more superior than in the dumb phone. I guess the manufacturerforesaw that thumb-typing on a small screen can produce a lot of wrong spellings. So the predictive texting tries to figure out what you are typing even if you occasionally hit an adjacent key and corrects it based on its dictionary.
Also unlike dumb phone predictive texting wherein you still have to type all the letters (for example, if the word has 10 letters, you still have to press 10 keys), the Samsung predictive text lets you just enter the first few letters. If you see that the word it predicted is correct, just hit space or some other punctuation and it performs auto-word completion.
If you type a new word that is not in the dictionary, it automatically adds it. It does not bring up a dialog box unlike Nokia dumb phone where you have to add the new word first.
Lastly, the predictive texting seem to learn which words you use most often and gives suggestion for auto-completion. Like in my case, just typing "Dr" automatically brings up "Dragonpay". The Nokia dumb phone dictionary is more based on just word frequency in general use and not specific to the user.