Ok I will try to tell you what I like and what I don't like.
We start of course with what I don't like or what I suggest to work on.
The first thing that caught my eye was that header and posts entrys are not aligned to each other. For example the navigation and the header title or the navigation and the post entries. Everything starts from the left side on a different point. That does not look good in my eyes.
I suggest to put the Rss elements on the right side of the upper navigation element where you have about and contact. If somebody is using your theme and have more than 5 categories or page links he will get in trouble with the rss elements. And btw make it contact and not contact me...sometime more that one person is using a blog and it just looks better.
Align the search element in the header same as the sidebar.
A centered title, author and tags will look awful with longer titles and lots of tags. I usually like the tags rather in the post footer, cause they attract people to fast to click them and go somewhere else instead of reading the post.
On the post page (single.php) you have tags under the post title and in the post footer...get rid of one.
Too much gradients for my taste. One color would probably look more professional. maybe you try the top color of your gradient as background-color and white as post and sidebar color. maybe also opposite. But that is anyway a taste issue.
What I do like is the generally choice of color and how you put that together with the upper navigation bar where about and contact is included. Also the hoover effects are well done.
The nested comments if you reply are good too.
All this are suggestions. What you will do in the end is of course still up to you. I hope you don't take anything said the wrong way.