Actually, the downside to the Solstice is the fact that they've been put on production hold at least twice due to quality issues. Lots of guys who have a Solstice on order are being told they have to wait longer for thier cars...much longer. And it's got the guys who've already taken delivery wondering what might have "gotten past the QC guys with my car???"
While I agree that the Sky is the sexier of the two GM entries, the MX-5 still tops them for flat out sports car performance driving. I've driven the new MX-5 and own a 1999 Miata. I bought the car because I wanted the classic small sports car feel, ultimately tossable in the corners. The MX-5 still wins in that regard, so say more than a few car magazines and online comparison reviews. But I'll just bet many people will view the additional creature comforts, larger wheels, etc on the Solstice as a bonus, and opt for one of those instead.
Still, when 2007 rolls around and GM drops the 250HP turbo motor in the Solstice, I just might be willing to overlook the superior handling of the MX-5. At least until the next generation Mazdaspeed MX-5 hits showrooms.