Smartcockpit used to host the user guide of that radar, sadly it has been removed.
We use it for the last 6 or 7 years now and the experience has been great, at least under european conditions. The weather picture in automatic mode is very clear up to the max range and makes it easier to plan strategically around the weather. In low level operation there is a trend for a bigger returns in auto mode, turn down gain a notch or two and it is quite ok.
Personally i prefer the auto mode over the manual one, but switching to manual is sometimes not a bad idea, if only to show how much more difficult it is to get a good picture of the weather ahead. Surprisingly the colleagues on our airbus fleet are not as happy as we are on the boeing with the same radar, apparently it shows there much wearker returns and therefore not enough of the weather in the area.