The HTC keyboard forces you to either use a suggested word or use the word you typed but you have to put it in the dictionary. This is really annoying when I'm just trying to edit a spelling or something, and I end up will all sorts of crap in the word library.
With stock Android, you can pick the word you type, but if you want it in your library, you have to tap it again. But here's the thing:
With HTC, when you type a few letters, the suggested word pops up, and if you hit space bar, it will automatically put that word in. If you tap to choose the word you want, it puts that word in and then you have to hit the space bar to go to the next word. This is terrificly clunky. And slow. It's basically normal keyboard typing except you have to go out of your way to tap on words.
After you tap to select the word in Android, it auto spaces. If you enter punctuation, it backs up and puts it in right after the last word and then adds a space. The only time you have to hit the space bar is after the end of a sentence, and then just once since there's already a space there. Okay, maybe that doesn't sound like a big deal to you. But what this does is fundamentally change the way you type.
With HTC, it's basically like typing on a keyboard only with a lot more errors. My concentration is on the keyboard, and I have to break it to fight with the word suggestion. The constant interruptions are wearying.
With Android, it's more like you're searching for words and then choosing the word you were looking for. So it's not like typing, it more like searching. And, typical of Google, the Android keyboard excels at it. If you start typing a name from your contacts, it's comes right up. Lots of tech terms and non-standard words I use are right in the dictionary. My concentration is on the words that are coming up, not the letters I'm typing. And as a result, it's so much more accurate. In fact, I never go back to fix my typos because there aren't any. It's just much more satisfying and less fatiguing to write this way. I actually wish my PC could do this.