If HTC was hoping to keep at least some of the One M9's details a secret, it's going to be sorely disappointed. Well-known tipster @Upleaks has posted three promo videos that reveal... well, just about everything. They confirm that the M9 will have a much higher-resolution 20-megapixel camera at the back, as well as an UltraPixel (likely 4MP) front cam for your low-light selfies. You'll also get Dolby surround sound from the One's signature BoomSound speakers. And that's just the hardware -- there's plenty on the software side, too.
The updated version of Sense shown in the leak isn't as dramatic a shift as you might have seen in the past, but there are definitely some noteworthy features. There's support for customizable themes, a widget that shows apps based on location (think context-aware launchers like Aviate), a new photo editor with effects like double exposure, and the ability to share media through three-finger swipes. There are still a few elements left to the rumor mill, like availability and the exact choice of processor (likely a Snapdragon 810), but it's safe to say that HTC's March 1st event will largely be telling you things you already know.
Update: Not surprisingly, both the Twitter post and the videos have vanished. However, we did manage to grab images of both the new photo editor and theming.