My work requires a substantial amount of chart drawings etc and after using OO 
for a while, I found some charting issues which i could not work around.

1)Pie charts
  - displaying values and label texts often results in clustering/overlapping 
between sections (especially small ones) often rendering the texts 
indecipherable. A suggestion would be to allow OO to automatically place the 
values and text (probably with the use of lines) away from each other.

2)Bar-line charts (2 axes)
  - Similarly, displaying values often results in overlapping in cases whereby 
the bar value on X-axis is extremely close to that of the line value on Y-axis.
One suggestion would be to allow users to chooose where to display values 
(above bar, inside bar, centre of bar, above point, below point, right of 
point etc). 
               
Another suggestion for both pie charts and bar line would be to allow users to 
shift the individual values around as if the values were in text boxes after 
choosing option to display.

Cheers!