Wifi only. I just couldn't justify the $129 extra for a 3g model. That's just a rip off, 3G chips don't cost anywhere near that much. The 3G Kindle is only $50 more and includes free 3G access (granted the web sucks on it, but still).
Combine that with the fact that I'm around wifi the majority of the time as I have it home and office, and get it at the hotel when traveling, and it just wasn't worth it to me personally.
If it was like $50 more I may have got it for the convenience of having it if I did need (i.e. if buying a month was cheaper than paying for the wifi at a hotel etc.). But for $129 more I just couldn't justify it given how seldom I'd even consider buying 3g access.