I'm also using an original Pre. (I waited a week or two to buy.) The phone's lagginess is beginning to get to me, and I'd like access to all that app goodness available for Androids and iPhones.
I mostly use it as a portable email device, and none of the email reviews light my fire, but somehow jumping from one abandoned OS to another (Blackberry) doesn't seem like the thing to do.
I do wonder if the ads, and having a locked-down device, will bug me. But a world phone would be useful. Everyone tells me I should go for a high-end phone, and not something older like the XPRT, although that has a real keyboard.
I may try the Photon while I am away in Germany, and decide if I like it, and who knows, maybe I'll go back to the Pre, or maybe I'll decide I really need a keyboard. I wish Sprint offered a high-end phone with a good keyboard, but I've tried the EVO slider, and its keyboard sucks, and no one uses it. I haven't tried the Epic, but it doesn't seem like its keyboard is used much, either, and that device is getting long in the tooth.
Sigh. If Sprint had picked up the Pre3 (or heck, if Verizon had before instituting tiered data plans) I would have just bougt that, and likely not missed the apps I've never used. But that's not going to happen. So here I am.