Had similar problem - got iPhone 6 on Monday, still "restoring from iCloud backup" on Thursday. After reading several of these threads, a combination of possible solutions fixed it:
1) I restarted phone (not sure necessary, but did it)
2) synced phone to iTunes on Mac
3) after several issues (e.g., failure to initiate sync, transfer data, cancel sync), it finally took and I restarted phone
4) now I found several apps (some I'm certain I had deleted in past) back on phone with shaded icons, so I deleted some again and selected the ones I wanted to keep to start them downloading. Some downloaded, some froze, so I deleted the frozen ones out of frustration.
5) restarted phone again, and no more "restoring from iCloud backup" message.
IMPORTANT NOTE: I use iCloud Match, and upon checking SETTINGS>GENERAL>ABOUT, I found my number of songs (indicating only those downloaded to my iPhone) showing 103 vs. 5 as listed there before my sync to iTunes. So not sure if it was phantom apps or a iCloud Match issue, but something was hanging it up, and this fixed it.