I don't like that it's hard to customize the title the way you want it, especially if you want to add multiple lines of texts. I have to use photoshop to make my title page instead, but it would be so much faster if I could make it in the program. I also don't like that there isn't music already loaded in, you have to go online to find your own music. I would like a small list of pre-loaded songs.
Shooting movies is also great now with the servo AF feature. My T3i required that I manually focused while shooting movies. With the servo AF, the camera will actually follow the moving subject adjusting the focus on the fly. I mean, your cell phone can do it and so could my point-and-shoot Canon camera, but their old DSLRs actually didn't have that feature, but now (well, since like the T5i I think) they do and it's very useful. Speaking of movie mode, I very much like that they added another step in the power switch for movie mode instead of requiring you to turn the knob all the way to the very end to get to movie mode. Now you simply flip the switch to it.
The T#i line is what they call a "pro-sumer" line, which is basically between a consumer line camera like a very basic DSLR and a professional DSLR camera, thus the term "pro-sumer." Typically what this meant is an DSLR with an APS-C sized sensor, decent resolution, and some hand-me-down professional features of pro-grade cameras from a few years ago. For this reason, sometimes it's not worth upgrading from one of these cameras to the next until at least a few generations have past (meaning if you have a T5i, it's not really a giant leap forward to upgrade to a T6i). However, the T7i is somewhat different. When I was doing research on what features it has and what it is missing compared to the pro-grade DSLRs that are considered "current" right now, I was surprised to find very little. The main differences really is that the pro-grade cameras have the LCD display on the top that would display all of your relevant camera settings, and then a few of them would also sport a full-frame sensor. Other than that, the differences are very minor. Something like maybe 1 or 2 frames less in burst mode or something like that. Nothing that would really jump out at you and make you regret not stepping up to the professional grade equivalent (Think it would be the 77D?). It actually has pretty much all of the big features of even their current pro-grade DSLRs, making the T7i probably one of the best prosumer DSLRs to buy.