it's probably comparable to the 3rd vs 4th gen iPhone. One difference being that the 3GS was a fast enough device whereas the pre plus is honestly unusable without overclocking, so I wouldn't expect anything to be released that can't run on the pre plus, maybe they'll have something impressive running on the 9th.
The screen resolution isn't as bad as people think. It's the same resolution as the Droid Pro and has a much better keyboard. If you want a phone with a smaller screen it's going to have a lower resolution. Like @spaces said, wait til Feb 9th. Everyone else is.