I'm doing a multi-part
blog-post about it, but a few quick things to consider:
I'm playing the game underspecced on the GPU-side (GeForce 840M), and so was fully expecting to have to lower the resolution. Experienced no performance issues on 1280x720. Most of the issues seem to crop up at higher resolutions, but there are some issues with certain graphic cards. Also, there seems to be a number of people that have GPUs effortlessly surpassing the minimum specs in processing power, but being too old to fully support OGPL 4.5. My card is somewhat newer than the one cited, but considerably less powerful. I had two crashes, both after extended sessions of over 6 hours, so nothing shocking. There have been serious issues with AMD phenom CPUs though. A first stability and performance patch is out, brought a noticable frame rate increase for me especially in the GUI, but the main thing here is that really the controlls are completely unoptimised for PC. There's already mods out fixing part of that, though.
For Orbiter players it might be important to know that the game has no semblance of realism in any of its aspects. High ability to suspend disbelief is required, though I find that the real scale planets make up for a lot of that. It's basically the main thing that completely put me off spore (not to say that the two games are very similar - they really aren't).
For people that are unsure, I would definitely suggest to wait for a sale, though. This thing requires a certain kind of player to fully enjoy. I'll elaborate more on that in the blog.