I’m totally used to the iPad’s soft keyboard, but when I go back to my iPod touch it drives me crazy. I miss the letters, I hit enter when I mean to hit shift, and I generally get angry. I would not, however, buy a phone with a keyboard ever again.
But I might consider the Spike, or more likely, the Spike 2. Both are iPhone cases with flip-open keyboards, but the Spike 2 improves on the formula by getting out of the way when you don’t need it.