As I said in the last review, the G1 is an indifferent phone. But when it comes to texting, it's really quite good.
That's not just because of the keyboard, although the keyboard certainly helps. As I intimated in an earlier post, one big reason I didn't go with the iPhone was its lack of a keyboard - or, really, any physical buttons beyond the single button at the bottom. It reminds me of Apple's one-button mouse. The G1 has four physical buttons plus the world's smallest trackball, which is arguably overkill, but I'm not complaining. I can choose not to use a button. But I can't choose to use one that's not there.
Without the keyboard, iPhone users have a problem. To use this elegant piece of hardware, they have to inelegantly hold it in one hand while repeatedly jabbing it with the forefinger of the other hand. Although the softkeys are not too small for everyone, I found them to be very hard to select in my in-store tests. Sure, I might get used to them. But I would still have to jab the device with my forefinger. No thanks.
In contrast, the G1's keyboard is like a Sidekick's, hidden beneath a screen that you slide out. When you do this, the screen orientation changes to horizontal and you can type with your thumbs. Both thumbs. In practice, this is a lot faster. (Although it's not as convenient as texting on the physical ten-key of my old phone with predictive text activated. I really liked one-handed texting, but that won't be an option on the G1 until someone comes up with a suitable soft keypad.)
The keyboard is small, and at first I was worried that it wouldn't be up to the job. But after a couple of days, I found that I was typing at a pretty good clip. The main problem is that I don't see any arrow keys or beginning-of-line/end-of-line options. Too bad! You can use the trackball to guide the cursor, but the trackball is oversensitive (it's about the size of a BB) and I find that I often jump lines or jump out of the field with it.
I'm disappointed that you can't seem to cut or paste text in the Messages program, too. You can cut and paste in GMail, GCalendar, and the Browser, but not across all programs.
So far, no surprises. But the messaging program itself is great. It divides texts into threads: every time someone texts me, their texts and my replies are put into an easily navigated thread. Threads are listed by interlocutor and alphabetized by their contact name (if they're in Contacts). If you text multiple people, it starts a thread with all of them and you can see all of the outgoing messages you send to the group. Android doesn't allow you to set up groups, but they would be redundant given the threaded functionality.
When you receive a message, G1 alerts you in the status bar (more on this later) and when you enter Messages, the active thread is marked with a green bar. I'm much, much better able to tell at a glance what messages I've received and to see from context what conversations are going on. And of course my Twitter stream is kept separate from my other conversations, which makes it much easier for me to make sure I don't accidentally send a personal message to Twitter or vice versa.
Overall, if you're looking for a phone primarily for texting, the G1 looks great.