Personally, I think he is a megalomaniacal jackass, who is not a real conservative, not a real Republican Party member, but he has tapped into a deep seething anger among a large sector of the American people. I don't know if it's enough for him to beat Sen. Clinton in November, but it's out there, and one can feel it. People are pissed.
The way to look at Trump is to understand that unlike many other democracies, America has only two very large, "catch-all" political parties. (We still have dozens of minor ones that are on every ballot, but Americans just don't vote for them.) So Sen. Bernie Sanders, Hillary's rival, belonged to a regional socialist party, but "caucuses" sits with the Democratic Party. Just as Trump is really, just using the Republican Party. He is really the American version of say, France's National Front, or the Netherlands' Party of Freedom.