The name didn't ring any bells with me but, since nobody else had replied, I thought I'd take a look at the site and see whether I could offer any general advice.
And then I realised I have bought from them.
Just once, a little over a year ago. I needed a couple of lens hoods which rather surprisingly I couldn't find on any UK retailer's site. (You do know that Photospecialist is a trading name of Foto Konijnenberg in the Netherlands, I assume.)
The web site was easy to use and I received an automated email to confirm that my order had been received. Literally two minutes later I received an email from a member of staff to say that one of the two items was out of stock. I was offered the choice of waiting for both items to be available, or paying a small extra delivery charge to split the shipment and get the first one immediately.
I asked how long the second item would take but they didn't know. I asked whether I would be able to cancel the order for the second one if it took too long, and I was told I could. And in the course of this email discussion, during which all my emails were answered within an hour, they offered to waive the additional charge for a split shipment.
The two items were shipped by UPS from the Netherlands, about a week apart, and I received emails confirming the dispatches and advising me of the tracking numbers.
So all in all, apart from the out-of-stock situation, it was a pretty positive experience.