WiFi is available, but not everywhere. What device to take? It depends on what you plan to use it for.
I planned to blog while on the Camino, so I needed something with a reasonable sized keyboard. I took my iPad and it worked out well. I did not use my iPad to take photos - I used a small digital camera, although I'd probably just use my cell phone for photos now. Nevertheless, I was easily able to transfer my photos from my camera to my iPad. I used it to Skype, listened to podcasts, and very occasionally read a newspaper or book.
If you just want to be able to stay in touch, Skype, check FB and e-mail, maybe just a phone would be enough. You'll be able to connect in enough places that you should never feel isolated (although, again, you won't be able to connect everywhere).
Referring to a previous poster, I did take it with me wherever I went, including the showers and dinner. I had no problems and I would probably take my iPad again.
FYI, my phone was a Samsung S4. Unlocked and bought a Spanish SIM card in Estella on the CF.
Hope this helps. Buen Camino.