If you get a Google+ account, one added benefit is that you can now upload an unlimited number of higher quality photos (up to 2048 x 2048 pixels) to Google+ and/or Picasa Web Albums, for free. There are some differences in how your photos are handled and stored, depending on if you upload photos in Google+ or in Picasa Web Albums. The details are explained here.
Picasa
Picasa Software: Web Albums Login Incorrect With 2-Step Verification
Using the desktop software version of Picasa, you have the option to sign in to Picasa Web Albums to upload and share your photos. If you get a "login incorrect" message when you try to sign in to Picasa Web Albums from the desktop version of Picasa, it may be because you have 2-Step Verification turned on in your Google account.