Most of the complaining about Politifact was that they declared the Democratic party claim that "Republicans voted to end Medicare" their "Lie of the Year" based on the idea that they were not voting to "end" Medicare, but rather to slowly transition Medicare to a voucher system. Democrats believe that the Ryan voucher plan slowly replaces Medicare with a voucher system that happens to be named "Medicare".
If you viewed the Ryan voucher plan as being a different program that happened to also be named "Medicare", then the Democratic claim was true. If you thought it was just a "change" to Medicare, then the Democratic claim was false.
If you viewed the claim as true, then Politifact taking a statement of fact and naming it their "Lie of the Year" is obviously going to strike you as pretty outrageous.
Right, Ryan proposed reforming Medicare and Democrats lied and said he wanted to end Medicare.