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