It's no better a higher levels, you cast the spells less often as they get stronger and the experience you gain doesn't go up enough. It's the only skill I have to gradually power level for it to keep up, otherwise my other skills will be 50-60 when restoration is barely touching 30. It just doesn't level, even though I'm constantly using it to heal in most battles.
Illusion is similar, you need to fury a good 3-4 people for the spell to gain one level to start off with, which is so much slower than alteration and conjuration. But conjuration seems to massively slow once you hit 40-45. The higher level spells just don't give enough experience.
Anyone else get this feeling? I don't want my skills to level fast and I never take the guardian/lover stones, I want a steady pace but for them to be roughly the same. Which just doesn't happen when using restoration.