1. He's the only one taking hard positions on amnesty, illegal immigration, trade agreements, etc. If he's lying about promised action, how is it then any different from everyone else who is dedicated to the status quo?
2. Secondly, why would he lie? These are extremely controversial positions; he needs the amount of attention it brings like a hole in the head. Whether he wins or loses, his privacy (such that it was) is completely shot. The rest of his life will be led behind a security cordon.
Obama campaigned on the promise of change. It's a nice, positive image that caused no controversy. He was a life-long under-achiever who was placed in his position - he had no real dog in the hunt because everything was always done for him. Therefore, when his hope & change pledge fell flat, no one was that surprised.
I find it impossible to compare the two men - you can't get much more different. It doesn't compute to me that Trump would take this much effort, engender this much heat, unless he really did care and was intent on making changes.
See, this is the part where I lose you. There are many reasons for him to engender this much heat. He could want to change things. Or he could be trying to amplify his voice (as I've heard some Trump supporters actually posit). Or he could be setting up a position that gives him wiggle room (remember that his policy paper on immigration was not a direct reflection of his stump speeches). I don't think you can dismiss these other possibilities so easily.
You know, I try to believe people when they tell me what they want to do. When Iran says it wants to kill me, I believe them. When Trump tells me (in his book) how he negotiates, I believe him. And so far, his campaign is going by the book. And I know that Trump is going to benefit from this deal (he'll get to be President). But what am I going to get (for sure)?