Talking about issues, I've noticed some header using a featured image behaviour that may not meant to be. I don't know if I should discuss it in this topic, but, as I think you're appreciating feedback, forgive me.
The main issue is the header using a featured image changing sizes depending on the featured image: 131px x 200px here http://sugardrops.wordpress.com/2010/11/15/pandora-hearts-2/ and
180px x 147px http://sugardrops.wordpress.com/2010/03/06/pandora-hearts/ here.
I've noticed not all posts with featured images make the header change at all from the default, presumably depending on size and image's proportions (you can also see that I've been playing around with them in featured posts in http://sugardrops.wordpress.com/ and, in fact, seems those who don't change the header get a different display layout - very nice!), but I don't think something heterogenous like changing sizes depending on the featured image, which is aesthetically unpleasant, was the theme developers' intention, and if it was, please think it over to make it more uniform: either by fixating a size for the headers using featured images, or by making the headers not change at all.
Still on the header issues, I've still not encounter this issue on my main blog, but on my test blog the featured image on the header, instead of being cropped like in http://sugardrops.wordpress.com/2010/04/07/happy-easter/, it gets squeezed: http://atestblogforiru.wordpress.com/2012/10/11/oh-this-is-a-test/.
Thanks for solving the previous issue, and I hope this was of any help.
Looking forward to your reply.