"I shall now render you--INVISIBLE! Oops..."

Fantastic Four was over twenty issues into its run when it was decided that the Invisible Girl's power of invisibility wasn't perhaps enough of an asset to hold her own in the high-stakes battles that the team was fighting. If that assumption is true, I'm not quite on board with it. I think invisibility in a battle would be quite an asset, providing Sue would adapt her style to use the power more aggressively instead of waiting for opportunities to present themselves. What I think was really the concern with Sue was that her power didn't make for very exciting artistry in the book; and when that's the case, you can't feature such a character that often in a particular story without detracting from the story's pace. Also, there are only so many times you could have foes looking bewildered and wondering how they tripped or lost their weapon before it would get old.

So it's no wonder that Sue was coming under fire from readers for being dead weight and not holding up her end on the team. To my knowledge, Sue was perhaps the first invisible character in a comic to have such an extended run of stories, and giving such a character decent *ahem* exposure wasn't yet a bridge that had been crossed for any writer or artist. Fortunately, the problem was mitigated by the fact that the character of Sue Storm seldom pushed her way to the forefront in battle and often held herself in reserve--but the time apparently came when the Invisible Girl needed to become more visible, in the sense of having her abilities play out more visually for readers.

That, of course, brings us to the development of her invisible force field, which came about from her exposure to radiation being given off by, ironically, equipment Reed was using to get a handle on her invisibility power:

The force field power seemed to come as a surprise--except to (naturally) Reed, who reacted as if he was expecting Sue to develop this and other tangents to her invisibility power:

For a good part of the issue, considerable time is spent introducing us to the "new" Invisible Girl, even making the point that her new powers left no doubt as to her value to the team. And how better to drive that point home than to have the rest of the FF be as impressed as she is?

Though Reed isn't through with patting himself on the back in an expectant sense, as Sue demonstrates another new ability that capitalizes on the power she already possessed:

While we're clearly meant to be amazed at this variant of her invisibility power, I'm not sure how much use it will be against a foe beyond it having a disorienting effect.  Nor does it make much tactical sense to render the foe you're fighting invisible--you want to attack this guy, after all, not hide him from your sight. And why bother to hamper Sue by rendering her visible whenever she uses this ability, other than to guarantee that the panels have something visible for the reader to lock onto?

In a little over ten years later, Sue would get a power boost from another piece of equipment, this time one belonging to a foe. No new abilities to speak of, but her increased power at least served to raise her profile for readers, as Sue herself makes sure to remind us of:

And in another five years, Sue, along with Reed and Ben, would have their powers revitalized by an alien weapon. I doubt anyone blinked an eye at Ben lifting weights or Reed zig-zagging around, but the incident definitely served to put more of Sue's hostage days behind her:

All of which is great for Sue.
But, somewhere, I'm betting Marvel Girl feels like ripping a phone book in half.