Picasa is certainly a capable program. Your examples of PP are excellent. When my students ask me which free editing software they could use, I give them two options: GIMP or Picasa. I tell them that if they like tweaking with software tools and options they may prefer GIMP, but for a good all-round editor with an easy to use interface they might prefer Picasa.
My only reservation with Picasa is not the product itself, but rather the way its owner chooses to ride rough-shod over the public's rights. An example being Google's latest move to combine a whole plethora of diverse product terms and conditions into a central one-size-fits-all take-it-or-leave solution that suits Google, but might not fit what users originally signed up for.
However, this does not detract from the capabilities of Picasa as a product, which you have wonderfully shown.
Steve (Bedfordshire, England) My Nikonians Gallery- please visit and leave a comment A Nikon in the hand is worth two in the bag!