Picasa is pretty much dead now. All the functions and more and built into "Google Photos". I used to use Picasa and was always frustrated with it. I used it both in Linux and in Windows. My main interest was the face recognition feature. This feature worked pretty well until it didn't. Meaning --- I would work for hours on my face recognition db tweaking the results and then it would eventually crash and all my work was gone.
Google Photos works better but is still not perfect when it comes to face recognition. The other day I mis-identified a face and BAMOooo! My daughter disappeared...just like that. Oh nothing was deleted, but now all her pictures are attributed to my Son. Correcting the situation is very tedious since I have about 100,000 photos.
Google Photo is no longer alone.... Amazon Prime Photos now has a similar product that I like a lot. It lacks some of advanced features of GP but it is an option.