I have used it before and I have a local version set up to test all the new modules and to design templates.
I've found it to be very easy to use, fast and responsive. From an administrators point of view, It's a dream to use and it generally has a good backend. Installation of modules is easy and the templating system is very powerful.
I've got it running locally on WAMPserver, which handles it with no hassle. However, I would only ever use Linux on a server, mainly because WAMPserver behaves more like Linux than Windows Server.
I am currently working on a large Prestashop project which I will post more details of in the future.
To end though, I would deffinatly recommend using Prestashop!