I use thumbs only, typing in landscape. Sometimes the letters don't preview. They still type, but I feel like the phone gets "stuck" trying to register what I'm doing. Then I end up hitting b or n instead of spacebar and it gives me some horribly misappropriated word that I end up sending anyway because I just don't care. Or it just puts a word in that it "thinks" I want, even though it's not even close to what I was looking for.
This always occurs when I haven't shut my phone off completely after a couple days, or if I'm running Safari even if it's just sitting on googles homepage