I tend to take a look but don't hit buy as I like to make sure I get the best price possible which allows my book budget to stretch further. My book purchases are 99.9% of the time done on my PC or laptop, it's a neat option allowing me to check if more books by author or related are out there and then without needing to get out my laptop or get onto my desktop, but like I mentioned most purchasing is done via my computer/laptop after I've checked various different shops to get the best price for the book(s) I want.
Also I find the whole browsing on the Kobo itself to be slow as when you go to next page of results you get the whole loading bar before it shows the page. There is something about that loading bar that I find annoying.
It's not just Kobo I do the same with my two year old Kindle. I've only ever purchased a couple of books direct from the device and I already knew that I couldn't get a better deal elsewhere.