I used ProtoShare end 2009/ early 2010, and just returned to it for a new project. While I like the new features and improvements, the performance is still less than satisfactory. I'm building a fairly simple shopping cart with a few pages, a few states on each page. Rendering the page, switching to edit mode, duplicating a page, duplicating elements on a page... each page refresh takes far too long. (I'm using Firefox on the Mac). I'm planning to use the prototype for usability testing, and I'm concerned that the performance issues will get in the way of the test. They certainly do get in the way of building the prototype, which makes me recommend this product only with strong reservations and caveats. Please do something about this issue, I can tell from a quick look at other forum members that I'm not the only one experiencing this.
And by the way, it seems to be taking quite a long time for my forum post to appear (my post from >16 hours ago is still not online). When users post questions on a forum it's usually because they're stuck for answers and are on a deadline. The moderation process needs to be made more efficient so that we can get our answers quickly.
I've always received very prompt responses when I directly email customer support, and I do appreciate that very much.