I just test drove a base Solstice a couple days ago. If I had the means, I'd go for GXP for sure, but I was pleasantly surprised with it. I liked it MUCH more than the Miata I test drove a few months ago, although it was a 2004, but still, I thought the Solstice was a much better car overall.
The ride/handling was great and there wasn't as much road/wind noise as I was expecting. I did find it a bit clunky, especially from a dead stop. Once you're out of 2nd gear it's fine but there seemed to be some clunks coming from the right front somewhere. You can tell it's a price-point car for sure but it was a 'new' 2006 that has been sitting on the lot for a year and a half.
The only issue with putting the top up and down was making sure you SLAM the trunk hard enough to make sure it's locked. It was easy to attach but I could see how it would get annoying over time especially if you're dropping the top a couple times a day. Didn't care about the trunk space at all, I don't think I've ever opened the trunk in my Solara yet.
I would buy this car in a heartbeat, but I wouldn't want to drive it in the winter so I suppose I'll wait until the Solara is paid for and save up for a GXP.