Here's something I picked up from Tim Ferriss. What he did was printed out a variety of covers, found a few books that was the same size as the one as his 4 Hour Work week and put the different covers on the book. He then took them down to the local bookstore and put them in the book store and sat there and counted how many times people picked up which book. The cover he went with was picked up many many times more than the others. You can find the talk on Youtube if you search for "google fireside ferriss"
That sounds like a smart thing to do, if you've got the time, especially considering that it seems like a numbers game to me.
I'm assuming Steve's goal is to sell as many copies as possible. I'm also assuming that even though he expects to make most of his sales online, he still wants to do decently well in book stores where people who are unfamiliar with Steve may buy it without recommendation. Meaning the book has to be able to sell itself, also meaning that the cover has to be able to draw someone in (without becoming disrepresentative of the content or Steve himself) and then the blurb or other information that people check after the cover has to sell the book in a short period of time.
The cover doesn't speak to me. It does't single me out, it just is, nor does it particularly draw me in. However, to me, at least, the cover is not offensive or particularly bad or ugly, it just is. Bland, like others have said.
So, yea, just test it, if you haven't done so already. Good luck! And yea, I'll be buying one.
Edit: I want to emphasize two things: I don't think the cover will hold the book back, it just might not be the best one to get the maximum number of sales. The second is that I think Steve knows that the cover (like the appearance of this site) is not going to be a major selling point of this book, the content is. 7 Habits has sold for many, many years with a so-so cover based on its content and I can think of a number of books like that, including many that are on Steve's book list. I think the book will be a best seller with or without a more engaging cover, if its anything like Steve's posts.