I have a T430s. It has both the keyboard backlight and the thinklight. I had an R500 before that had just the thinklight. I very, very strongly prefer the keyboard backlight for three reasons:
1. no reflections on the keys
2. part of the thinklight reflects off the screen, reducing perceived contrast (=(Imax+k)/(Imin+k) where k=ambient light)
3. for some reason, I even find the backlight helpful in broad daylight
I didn't think it'd make so much of a difference before I got the T430s, but for what it's intended it's just vastly superior. And I've found that now that I have the backlight, I don't actually use the thinklight all too often anymore, even though it's only two Fn+Space away.
1. no reflections on the keys
2. part of the thinklight reflects off the screen, reducing perceived contrast (=(Imax+k)/(Imin+k) where k=ambient light)
3. for some reason, I even find the backlight helpful in broad daylight
I didn't think it'd make so much of a difference before I got the T430s, but for what it's intended it's just vastly superior. And I've found that now that I have the backlight, I don't actually use the thinklight all too often anymore, even though it's only two Fn+Space away.
YMMV.