When I first bought my 3rd gen iPod Touch I never really used ambient light sensor, in fact it never seemed to work quite right or so I thought. I used to manually adjust the brightness as I needed and it wasnt all that often that I needed to anyway. However once I sussed it out I left the function on permanently. So with that said, I think I could once again go without it.
Having quick access to the brightness setting on iPT5 would be a big plus. Hopefully Apple will come up with something that can do this in a future iOS release. An SBSettings panel built into iOS would be awesome.

I'm guessing once I get used to the sensor not being there then it wont be bothersome. It's like anything else in life, some things improve and come into existence while some things just disappear. We adjust and move on.
From all the comments I've been reading all over the web, all the PRO's very much outweigh the CON's. And pretty much the only CON so far has been the missing sensor.
If Apple were truly consumer focused with the iPT5 then their 'action plan' (if they have one) should have looked like this:
- Removed Feature: Ambient Light Sensor
- Replacement Feature: Quick access brightness adjuster on lock screen and home screen.
I mean if they're going to take something away, at least replace it with
something. Even if it isnt as favoured as much as what they're taking away at least it provides us with an alternative solution.
Maybe the 6th gen iPT will have the sensor built into the front facing camera somehow......... or will Apple make the iPT even thinner and say "well we could no longer fit the cameras in because we wanted to make the iPT 6 the thinnest iPod ever"... LOL

....... hmmm, I think Apple need to call it quits on the 'thinness' infatuation.