The Mazda3 has always been criticized for its small passenger compartment but this generation is reasonably roomy (except for that trunk issue).
I find getting in/out of the back seats to be an awful affair and MIL always keeps one back seat folded because her golf clubs don't fit exclusively in the trunk. The front seats are fine, except that the car is narrower than others in the class (and so, elbows touch if you share the centre console armrest).
Of course the other controversy here is the tablet “stuck” to the dash but it works well, don’t dis it until you try it.
I have tried it. I continue to 'dis' it. The knob does make a lot of sense. I like that it has redundant controls (i.e. touchscreen and the knob). I like its placement (less view-obstructing). HOWEVER, in MIL's, the screen has now been replaced twice (it complete dies), and it looks utterly out of place. It needs to be better integrated than it is. More importantly, it needs to work: hers is not the only example of it dying.
On paper, the Mazda3 seems like a winner...but after some time of ownership, people are finding that it's not such a great car after all. Great to drive, seems to have a lot of value in what you get, but I disagree. Resale isn't great, reliability isn't as strong as many of its competition, and liveability is touchy with the outward visibility.
MIL will continue to buy because she likes the sales manager there, but she is not so in love with the Mazda3 now as she was with the first two she owned.