I've had some requests to make the transparency of the widgets to be configurable, unfortunately after many attempts.. it just does not seem possible. I took a look at the existing widgets and noticed that the transparency is set pretty low, so I increased that a bit and made the text colors much more readable. I also added a new 4x4 widget that is mostly transparent.
NOTE: Once this update is released, you will need to readd widgets to your desktop in order for them to work properly.
Here are some screenshots I took with all the widgets loaded up on a tablet (10in screen).