My take on these talents is that while they are an annoyance to keep up and all that has been said here, people seem to lose sight of one important plus of these talents: they are POWERFUL. I use Invocation on my Frost mage and 25% extra damage? HUGE. I know I was complaining about them before leveling to 90, and not looking forward to them. But in the past weeks it has been very rare that I am not top dps by a good margin. As said on a similar thread here, the way I see it now is like this: during Cata Arcane had the whole burn phase/conserve phase dynamic that some people found fun. Now with Invocation you have a 40s burn phase and ~5s conserve phase. I think spending a few seconds channeling is a small price to pay for absolutely destroying dps meters.