Aftermarket tint (as well as factory) requires a bit of extra care...
It is prone to scratches (so NO decals, especially if you have to remove them later).
NEVER use Windex or any ammonia-based window cleaning product, or the tint will discolor (Sparkle, the purple stuff is fine).
I've seen some aftermarket tinted rear window develop bubbles near the electric defroster elements. This problem may/may not have been corrected with the latest technologies.
Check with local laws regarding the use of tint and the allowable tint percentage. I had limo tint in my VW show car a decade ago which was okay in Illinois, but was forced to remove them from the front windows upon residing in St. Louis.
If you change your mind about the tint later on, you can use a hair dryer to remove it completely without any residue.
2009 ML350 (84K) - Family vehicle
2001 CLK430 Cabriolet (71K) - Wife's car
2005 BMW 645CI (124K) - My daily driver
2012 Mustang V6 (60K) - Daughter's car