Everything should illuminate pretty evenly.
If the entire climate control panel is dimmer than say, the gauge cluster, then it's probably fine.
If a portion of the panel looks a bit inconsistently lighted, then it probably is.
Amazing what difference a single burnt-out bulb can do...
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