which T4i kit
I also have the 18-135 STM and it's really a good lens. It is my first IS lens and I find it amazing!
I bought it mostly because of the good reviews, and for future use of STM in video. I find myself not using video much for now.
However, to my surprise, I also find that the focal range is great! I own other lenses, but I don't switch as much as I used to in my film days. For film, I had a 24-85 3.5-4.5, a 50 1.8 and 70-210 3.5-4.5 I used to switch all the time from the 24-85 to the 70-210, and would rarely leave home without those two. The transition point of about 80 was in the way for most of my general or family shooting. Translated to crop sensor, this is about 55. Had I bought a 18-55, I would be switching lenses as I used to.
The 135 end is long enough for general purpose. I just find the 18 end to lack a bit, 15 would have been better.
Even the 50 1.8 and tripods see less use now. The IS doesn't cover all situations, but it really extends the zoom usefullness in lower light situations.
It maybe a minor point for you, but the 18-55 are not supported by Canon Digital Lens Optimizer. This features allows for automatic software compensation of many lens aberrations. The 18-135 STM is supported.
Get the 18-135 STM!