Creating an open-source video player that plays most formats you throw at it is no mean feat. Not only is it a complex programming task, but there's also the 800-pound gorilla, VLC. So how does an open source development team go about competing with such an established free alternative, and does SPlayer have anything to offer to users over VLC? In a nutshell, SPlayer does it with style.
Whereas VLC has a somewhat utilitarian default interface, SPlayer brings some pizzazz into the picture. The controls are carefully styled and skinned. SPlayer also features a "theater mode"; that's a fancy name for starting up in full-screen (you can do the same with VLC, albeit with the command line options).
Another feature that distinguishes SPlayer is subtitle auto-fetching. As you load a video, SPlayer does its best to identify it and download subtitles for it. It then overlays those subtitles on the video as it plays, without you having to do anything. The entire process is seamless, save for one major flaw: The subtitles aren't always in English. I received some in what may have been Serbo-Croatian--with diacriticals showing incorrectly, no less. Still, if you're into foreign films, this is a very compelling feature.
SPlayer also attempts to make video more social. The "people" icon on the left of the control bar is used for "checking in" with your friends. It lets you share the filename of the video you're watching, a rating, and any other comment you wish to make using services from Sina or Tencent, two sharing tools popular in China. Twitter (and English) support will be added in the future.
And that brings me to the next point: Localization, or lack thereof. SPlayer is squarely aimed at Chinese-speaking users, with a complete Website and a documentation wiki in Chinese. It does have an English-language Web site and UI localization, but it is only partial at this point. The menus and tooltips are available in English, but the "check-in" feature and technical documentation are Chinese-only at this point. Once you get used to the player this may not be a big disadvantage, but it is something you should be aware of. Of course, if you read Chinese this is a non-issue, or maybe even a plus.
The last thing I'd like to cover is the first thing you'll do with SPlayer: installation. On two out of the three machines I've used for testing SPlayer, the installer ran without a hitch and completed quickly. The third machine, the only one running Windows 7 64-bit, was not as smooth. The installer consistently hung at the last stage of installation, showing "Unregistering DLL" and crunching loads of CPU time. I eventually had to kill the process. Once I did that, SPlayer worked smoothly on this machine.
Another note about the installer is that it seems to toggle between the Chinese and English interfaces: On first running it, I got a Chinese-speaking SPlayer. I then ran the installer again, and the SPlayer interface automatically switched to English. I verified this a number of times on two machines, and it seems like an intentional feature. SPlayer does offer a way to switch the interface language from within the menu.
All in all, SPlayer is a highly capable video player in an attractive package. If you don't mind the imperfect localization, you should definitely give it a spin.