I also use Woocommerce and bought Kriesi theme and I have Canvas theme from WooCommerce as well.
Kriese theme features a powerful and simple framework, especially if you like Slideshows or build complex pages since you have what they call Dynamic Templates. Where you actually can mix different contents of different pages in one Dynamic Template and reuse content automatically in different pages builds you make, it is like a kind of "Lego" where you just take parts and build a page.
Also it integrates BBpress Forum and the Product Page features a Slideshow, something I have not seen in any other theme.
They guys in the kriesi website are very supportive through their forum. All in all I find the Kriesi themes really elegant, dynamic and powerful.
Woothemes on the other side IMHO are less elegant than other themes I have seen and the support of the Woo team is slow and lacking, there have been a lot of complains among their user base, so many that they have written announcement a few days ago saying that they are building a new support system (on Zendesk) to improve their support attending the complains from their customers for such a poor customer service.
On the other side the wooteam updates their framework and themes on regular bases, monthly or even weekly, something you don't easily see on other developers. I'll use both thems, Kriesi and Woo in different projects and see how it goes.