I have an 03 Vti, 06 Altis.
The Civics key set: There is one individual key with a separate remote. Strong, durable and very high quality. Never faced any problem even though it has fallen (even in water/mud) several times.
The Corollas key: I guess the one they gave me was crappy, but it fell from about 3 ft onto marble flooring and broke. I went to Toyota for a new cover, they said we cant, you have to change all the locks, switches, ignition, eveyrthing for Rs. 19k +2k installation and 1 day at dealership. (2 yrs ago) I said no way
I then went looking around for a cover, but the original has only 1 screw (cover to key connection), and the after market cover has 2. So I couldnt do anything, finally winded up getting an alarm system :@
Maybe my key was defected, I dont know. But my experience is that Toyotas keys suck!