The box contains the speedlite, a protection bag, a ministand, a bouncer (which was surprisingly because I didn't order one) and a short manual.
The first thing I noticed was that this speedlite is very similar to my Canon 580EX II. Especially if the two speedlites lay in front of you there is not much difference. But if you have them in your hand you'll notice the difference. The canon unit feels a lot more solid but for nearly four times the price. Nevertheless the overall build quality of the YN 565EX is good. The battery chamber cover is build very nicely and similar to the canon's cover. The head rotates 90° to the right and 180° to the left. The hot shoe has a metal plate but the rest looks like made of plastic. The control buttons on the rear are made of a kind of hard plastic and are fine to use.While the YN 565 is missing the wireless master function and HSS it has at least one additional feature the canon don't has. It is able to beep. Sounds simple but this is very useful. Every time you fire the flash it is able to give you direct feedback if the exposure was right and if it is charged again. Especially if you have the unit buried in a softbox this helps a lot.
Mounted to the camera you can control it directly from your cameras flash settings menu. It works similar to the canon speedlite. The most interesting feature is wireless mode. You can use the 565EX as a manual flash which fires if other flashes fire (S1 mode). The S2 mode works the same way but is able fire at the right time if there is a kind of preflash. The third slave mode is the wireless ttl mode. Once you configured this you can choose a group (A,B,C) and a channel (1-4). That's it. The rest is controlled by the master unit. No more running to each speedlite to adjust it. Just dial in the settings using the cameras flash setting menu and you're done.
Another improvement over the 580EX is the focus assist light. It is extremely bright. See the following picture for the pattern it projects. While this is very helpful for the auto focus it might annoy people which are in front of the flash :). The YN 565EX is a well build speedlite. Mounted to the camera it lights everything in a satisfying way. Especially if you use it as a slave unit you'll be happy with it. It supports wireless ttl, is very strong and finally a bargain compared to the camera manufacturers gear. If you don't need the ttl stuff have a look at the YN 560 II.
For an in deep review visit this page: Yongnuo YN-565 EX Flash Review