With complete respect, Adam (Avaran), I think your golem concern is unfounded. I was one of the big opponents of golems back in the day, too, so I totally understand where you are coming from and the similarities you are seeing. However, I think you are missing one key difference between golems and paragon paths.
Golems were particularly problematic because they could cover the "holes" in a build. Players didn't just pick a random golem. They picked the golems that provided the immunities, abilities, and benefits that their base class didn't. As a result, golems provided a ridiculous amount of "free build."
Point well-made. Thanks for pointing this out, Mike.
I'm still trying to think my way through what I think of Paragon Paths; in some respects I've mostly been thinking out loud to get other opinions.
I think the thing for me about Immunities is that in my way of thinking, whenever someone gets to call "no effect!" they have gotten an amount of free build equal to whatever that defense would have cost to negate - whether a Spell Shield, a Cloak or Bane, an Elemental Shield, a Spell Parry, etc. The value of that Immunity is proportional to the number of times a player gets to call "no effect!", and often there is no ceiling to that value. There is also an opportunity cost value, because that individual doesn't have to worry about counting/keeping track of defenses, nor do they have to worry about re-casting a dumb defense on themselves "just in case", which allows mental focus and strategy to lay elsewhere.
Maybe that is a poor way of looking at it? Or at least, maybe there is a better way to think about it? I'm certainly open to other viewpoints on that subject.
Part of me is just wary about it, too, because I had to deal with a fair amount of Golems and Immunities at one point (not NEARLY as bad as some chapters had it though); we (plot) tried various methods of dealing with them and ended up just ignoring them from a scaling perspective with the thought that it's a fantasy game, there's a certain level of power that comes with being high level and or in a golem, and there should be benefits - if a player wants to feel like a bad ***, then by all means, they should have those opportunities! Whether it's saving their friends or facing down a bad guy! I have to admit that my players seemed to naturally govern themselves and went out of their way to not break things.
And perhaps this will end up being more like a Controlled Spirit Store-like situation (but without the headache of being immune to Spirit rituals and the wonderful headaches that provides, and with a timed effect rather than always-on).
As far as teams are concerned, will there be a push for each person on a high enough level team to have an Immunity so that they can say, "Oh, it's throwing Curses, this is Scholar Sonya's time to shine!" or "This guy is a Command freak and throws lots of it, time for Warrior Will to step up and Immune our way to victory!"? If so, is that something that owners and plot reams are prepared to deal with? Player mentality has often been about finding the best, most efficient way of dealing with a threat, and Immunities provide a very easy target for that mentality.
There are also "effective immunities" provided that practically have no limit - as an example, a level 5 Ravager is effectively Immune to Binding Effects (Slow, Bind, Release, Repel, Confine) - with no limit, only choice - by being able to 'choose' to take them as a Slow.
Another concern I have related to Paragon Paths, is allowing players to swing take-out effects (Elemental Death) or "Hindering" effects like Weakness, basically at-will for 10-minutes+. Some of these are simply powered by "any <x-class> ability" and allow for the person to swing, say, "10 Weakness!" If I have 11 Parries, that's almost 2 hours of 1 person being able to swing the Weakness carrier. What is plot going to do if there are 4 or 5 or more people that can swing Weakness for 20-50 minutes a day? Is plot then going to increase the base damage of monsters to compensate in order to ensure they are effective and remain a threat? Are the monsters then going to be Immune to the Weakness effect so they don't need to do any compensatory scaling? I can cite additional examples, but I think you get the idea if I've explained correctly.