Please don't think I'm sounding harsh, but I have constructive critisism:
1-The site has no purpose, no call to action. People will come to this site and think "Cool picture, now what?"
2-Since we are on the subject, what is the purpose of the site? Are you trying to get perspective clients to use you as a photographer? Did you just want a place to showcase your images as a hobby? Are you trying to sell prints?
3-I'm going to assume that you are trying to get perspective clients, or trying to sell your photos (your about us page mentions purchasing stock photos etc.) If that is the case, say it on the home page. People on the internet are generally very impatient. You literally have about 10 seconds to tell them what your site is about, and that it is exactly what they need (if they are in your target market).
4-Your site is so plain that it lacks personality and identity. I understand that many photographers want the photography to speak, but you still want the site to say something about you and your personality. Put your logo somewhere on the page (I'm assuming that your logo is the watermark), preferably at the top left.
5-Your site loads slow even though there isn't really anything on it. This is because you saved your image in too high of a quality. If you use Photoshop, use the Save For Web feature, save it as a JPG, and adjust the quality slider to somewhere between 70-80%. It will instantly show you the estimated file size, and image quality. For most photos you can't see any difference in image quality in that range. But if you can, and it isn't acceptable, just bump the slider higher.
6-I agree that there needs to be some other form of navigation other than Previous and Next links. A grid layout where you can click images to enlarge them, or something will go a long way for usability.
7-If you want your site to show up in search engines, you will need to textual content.
I'll gladly answer any questions you might have about my comments. It's getting late, and I'm tired so there is a chance I'm not making any sense.