There always comes this argument about whether your character should be able to become overpowered or not, but in my opinion a game should always be challenging - even at your character's strongest you shouldn't be able to cast one spell easily and then be able to just run through every quest or it wipe out an entire town unless maybe it has some super-awesome animation, long cast time, etc. - all of which 100% chameleon didn't. Chameleon 100% was just something you could use to get through quests without any work whatsoever.
Depends entirely on how its balanced, along with how it integrates with things like the magic-regeneration rate and what-not. If 100% chameleon was something I could legitimately use every 5 to 10 minutes for, say, 10 to 30 seconds, I don't see what the problem would be.
And frankly, if they adjust things to where its more effort to get to 100 than what's been present in previous games, I still see no problem. I hypothetically invested my work in getting that skill up to par and getting my magicka pool ready enough to do what I wanted it to. Perhaps the spells I get as a result shouldn't be press-key-to-win spells, but they should still have extreme utility.