Conclusion: The Speedlite 270EX II does a fine job when used on-camera, but the slave feature is only marginally useful. Because having to aim the flash head toward the mastter (in my case, this is my Rebel T3i camera) in order for it to receive the signal emitted by camera's built-in flash, defeats the purpose of slave operation. Canon should have positioned the sensor on the 270EX II in a more omnidirectional location in the Speedlite.
Pros: quiet, Good Exposure performance, Superior build quality
Cons: Slow recycling time, difficult to use as a slave
Conclusion: I purchased this small but mighty Speedlight because my 5D Mark III doesn't have a built-in flash. I already have a 580EX II, but don't always need the 'big-guns', with all of the manual overides and fuul power etc. The 270EX II is TTL compatible, but there are no manual overides or pretty much anything but an on/off switch and a slave feature. Great for 15' and less, bounce (but no tilt-swivel), fill-in flash etc.
Pros: quiet, Good Exposure performance, Superior build quality, pretty good value
Summary: Just not sold that this was the right flash. Bought so I would have at Christmas but found I didn't really need it with my T3i and in the settings I used my camera. We'll see this Friday when I have an opportunity to do more shooting outside and don't have the same lighting available & will be working at different distances to see how it works.
Summary: This 270EX II has more power than the Canon T4i built in flash. Since it uses 2 AA batteries, it is compact and lightweight. Flash head is adjustable for wide and tele setting, and can tilt for bounce lighting. Works good for outdoor fill flash. I'm very satisfied with this purchase.
Summary: I bought this flash for my new Canon G15 series camera. Since the camera is not as large as SLR cameras, it is a perfect size for this camera and other smaller cameras and fits very easily on the top of my camera. It also only takes 2 "AA" batteries which is much nicer that a previous one I had which was bulky on top of the camera and took 4 batteries. It has enough power to compensate for the lack of light from 10 ft. to at least 30 or 40 ft. away.