If you have yet to get into Picture Puzzles as a way to while away idle time, when you would normally head for the Jigsaw Puzzles instead, you may find that the lack of visual clues like borders, shapes and other patterns that make jigsaw puzzles relatively easy to solve, are far away from how you have to tackle these things.
They can be utterly frustrating, especially the ones labeled “Hard”!
Well your thread sank like a stone, but I’ve been doing the puzzles from there the last week. I’ve only been doing the “hard” ones. I wish more of the puzzles were landscape oriented, since they fit my browser screen space better.
My success rate is pretty low in that I bail out on most of them before I get them half finished. Now and then the right combination of colors and patterns will let me get the thing organized enough to finish it. But those are rare times.
I have been back over past puzzles a few times and will eventually work one I gave up on earlier.
Thanks for saving this thread from the “0 replies” fate so many of mine have had. 
Similar puzzles can be found at freejigsawpuzzles.com.
These look like fun, I’ve bookmarked it.
I’ve tried a few of them out, and they’re fun, but the user interface needs a lot of work. When you’ve got a block of a dozen pieces together, and want to move it around, you shouldn’t have to click a dozen times: You should be able to drag-select. And they didn’t make it as obvious as they could have which one is the primary selection, which affects how the block moves around.
Oddly enough I find these a lot easier than a regular jigsaw puzzle. Maybe it’s the regularity of the way the pieces fit. I had one slightly tough one; it was an abstract image and the last few pieces to fill in were very slightly different shades of black.
Not happy with the interface, either. It should be possible to create a ‘group’ of pieces that you think go together, and can move them more freely. What I least like about the group move now is that it doesn’t auto-deselect the moved piece (and you have to click on the ‘primary’ piece only to end it). This is obviously done because it’s such a pain to select the group, but it ends up making the interface worse.
The difficulty with locking pieces together would be that if you had a few locked groups, it would make it awkward to move them around without breaking up other locked groups.