I bookmarked the link to my picasa web space (https://picasaweb.google.com) which i uses to access picasa. It may get redirected to google+ page if you have opt-in to google+, but look out for a yellow dialogue box at the top of the browser which allows you to go back to the picasa web page. Once you've moved back it will (for now) always go back to the picasa page.
Personally I have nothing against the switch, though I understand the frustration of being forced to adapt to such changes without first being asked or informed about it.
Google+ apparent upscaling for small images is a bug in the service, which has now been ratified. Uploaded images will now retain their dimension.
FB uses a more aggressive compression algorithm for images, and the outcome is often worse than those uploaded to picasa/google+. If comparing between these two, Google+ will get my vote for being the better site to host photos.