Inflation is basically a concoction to explain away the several serious problems with the Big Bang Theory, namely...
1. The Horizon Problem
2. The Flatness Problem
3. The Galaxy Formation Problem
4. The Antimatter Problem
Here is an excellent source which explains in layman terms what these problems are:
http://hyperphysics.phy-astr.gsu.edu/hbase/astro/cosmo.html#c5
And here are some things I found some time ago on inflation theory...
Alan Guth [inventor of Inflation theory]: "Those 'little creatures'[cosmic microwave background photons], however, would have to communicate at roughly 100 times the speed of light if they are to achieve their goal of creating a uniform temperature across the visible Universe by 300,000 years after the Big Bang." http://nedwww.ipac.caltech.edu/level5/Guth/Guth2.html
As Albrecht, now at the University of California at Davis, puts it, inflation is not yet a theory: "It is more of a nice idea at this point."...
"The model in Guth's original paper, published in Physical Review D in 1980, admittedly did not work. Michael Turner of the University of Chicago, who took part in Bardeen's calculation of the density perturbations, says Guth had been brave. "One of the striking things about [Guth's] paper," Turner says, "was that he said: 'Look, guys, the model I am putting forward does not work. I can prove it doesn't work. But I think the basic idea is really important.' "
In fact, Guth's "old" inflation ended too soon, and too messily. A "graceful exit" was needed to make the universe look remotely similar to ours. In 1982 Paul Steinhardt, another co-author of Bardeen's calculation, solved the graceful exit problem together with Andreas Albrecht; Linde also found a solution independently. Their "new" inflation worked by adjusting the shape of the potential function, a sort of mathematical roller-coaster that defines the properties of the inflation.
Most of the mechanisms proposed ever since rely on carefully adjusting the shape of the hypothetical potential function. None, it seems, has been too convincing. "All these models seem so awkward, and so finely tuned," says Mark Wise, a cosmologist at the California Institute of Technology.
Physicists would like a theory that avoids such gimmicks, one that shows how things ought to be from first principles—or at least with the smallest possible number of assumptions. "Fine tuning" is the opposite.
It was two fine-tuning problems, two such implausible balancing acts, that inflation was supposed to have solved. "You're trying to explain away certain features of the universe that seem fine-tuned—like its homogeneity, or its flatness," says Steinhardt, now at Princeton University, "but you do it by a mechanism that itself requires fine tuning. And that concern, which was there from the beginning, remains now." As Albrecht, now at the University of California at Davis, puts it, inflation is not yet a theory: "It is more of a nice idea at this point." "
http://www.symmetrymag.org/cms/?pid=1000045
Translated as “we have no idea what we’re talking about, and no matter how much we massage the data, our fancy computers can’t even spit out something that makes it seem like we know what we’re talking about.” Back to the drawing board...