Jigsaw World is a nice collection of jigsaw puzzles which includes images with different themes. They include lots of flowers, desserts, houses, landscapes, means of transport and animals. The puzzles include different amount of pieces, so some are more challenging than others.
All the puzzles include different help options for different skills levels, so you can choose whether you wish to use them or not. What is great is that you can also modify the puzzles the way you want. You can select the number of pieces, pieces shape, and allow rotation or not. They are not timed, so you can take your time to solve them. You can show a thumbnail of the image or a ghost image in the background for guidance, show only the edges, and ask for a hint which will reveal two pieces that go together. From the options menu, you will also be able to customize the background color and adjust the music and sound volume. The game offers simple but nice graphics and sounds, and pleasant music.
All in all, if you like jigsaw puzzles, I recommend you should try Jigsaw World.