I've had this review queued up for exactly eight months - in the interim there's even been a new Chromecast version released (which I have not written a review yet, despite buying one to have it alongside my four original versions) and the anticipated features added for Chromecast apps. When the original Chromecast was released, I initially bought one in the hopes that Google Slides (their replacement for Powerpoint) would soon be able to send a presentation from a smartphone to a Chromecast. Of course, I didn't have this ASUS S1 projector as a display device at the time; I was thinking of a conference room with a flat panel TV already in place.
The ASUS S1 projector does have a full-sized HDMI connection which I have also connected to my tablets and Chrome OS devices, but it is also a natural fit to have a Chromecast there. Especially since the S1 supplies a USB power connection and is able to operate from an internal battery, that combination is entirely wireless. With the Google Slides app now being Chromecast-enabled it is a small presentation system, however you will need Internet connectivity (since your slides are hosted in the cloud).
Like all projectors, the room lights will need to be dimmed or turned off. The ASUS S1 does play the audio from the HDMI interface from an internal speaker that is often quite sufficient, and also has a 3.5mm headphone jack for external speakers. A full battery charge probably would not run for an entire movie, but I've easily done half-hour periods without powering the projector from the wall charger (19VDC).
I'm very well pleased with the picture quality and features. At the time I bought my unit it was $300 USD, with fluctuations of about $15 either way since then. There is not any included tripod to use the standard screw mount on the underside, but they are easy to find for the display characteristics you have in mind.
Next up is when I pair an ASUS "Chromebit" (an HDMI dongle larger than the original Chromecast) that runs Chrome OS with the projector, stay tuned...