I installed one in my 4Runner about 3 months ago give or take.
I have seasonal allergies so I wanted to see if I'd notice a difference when it gets to pollen season. I haven't been able to test it in that scenario yet but it seems to be doing performing as expected otherwise.
You will notice a significant reduction in air speed within the HVAC system however. The lowest setting isolated to the front driver vents produces only the slightest perceivable stream of air. I would consider this setting no better than "OFF". If you install this filter expect to go up a fan speed setting for your everyday usage.
By the summer I should have a more clear idea if the filter is worth it.