It's slow to get started, even on my pretty fast (20Mb/sec) broadband. I'm using Safari on 10.6.8.
I spent a while working out how to stop the (far too rapidly changing) slide show, since on my MacBook Pro the thumbnails across the bottom aren't visible and there's no hint that it's even possible to do.
Once I'd managed that, I found that the arrow keys don't work. For me, that's very bad.
Using the thumbnails is tedious: I spent a lot of time clicking on a tiny sliver of the next photo at the right-hand end.
So, FWIW, my view is that this is not a site on which I would wish to spend time, despite the many rather lovely photos. I think you could manage a lot better, perhaps with some help if, like me, you don't fancy HTML coding.