First question:

He did well enough to win 49 states in 1972 and rack up a 67 percent approval rating heading into his second term, in contrast to four years earlier where the nation looked like it was on the verge of civil breakdown. He had won whole demographics that had never voted Republican before-not even General Eisenhower could remove the ghost of Hoover for a lot of working class Northern Catholics or Southern Protestants. I think that kind of speaks for itself. You don't get that through dirty tricks or an easy opponent alone, you get that if the American people are immensely grateful to you for one reason or another. Had Nixon collapsed instantly and died in late 1972 or early 1973, he would be unquestionably remembered as a solid President who inherited the third most nightmarish overall situation in US history(next to Lincoln in 1861 and FDR in 1933), foreign and domestic. He'd probably be remembered as a tough, somewhat shady SOB who wasn't lovable but was hyper-competent and cleaned up the messes he got effectively, if not prettily.

The second question... this is going to be perilously close to going into political opinions, but I don't really know how to answer this otherwise:

No. Nixon was a highly complex personality ruling in a highly complex and emotionally charged era, so this is something that is always going to be debated, but I think it's always going to be "no".

He was a fascinating President. Nothing like the boring, 2D mustache twirling caricature you'll still see a lot. He could have been out of a Dostoevsky book. He was stranger than substance, capable of the most aching kindness and the most vicious, petty cruelty at the same time. He was capable of the most shockingly prescient thought of what the world would look like in 20 years and of the most stunningly ignorant small-town prejudices and conspiracy thinking. He had multiple personalities.

He was a tragic President. Not least because unlike most of our bad Presidents, he had the potential to be a good POTUS. He had the work ethic, the intelligence, and the political skill in spades. Had he wanted to take a different path in life, I'm pretty sure he could have grabbed a chair in international relations or law at any of the finest universities in the US-in other words, he didn't need a government job to make a living, unlike many in the American political class. He was genuinely creative and far-sighted in a lot of his policy ideas. (Nixon was fundamentally a man of writing, not speaking, who functioned best alone with his thoughts. Subsequently, his best side can be seen in his memos and notes, in stark contrast to the tapes.) And in spite of his extreme lack of feeling for the "human factor" in politics, everybody who actually knew him, even ideological antagonists(Bill Clinton), will state he honestly cared about the USA, did what he thought was right, and wanted to serve the nation.

He was an accomplished President. There's no rule saying he can't be this yet still not be a "good" President. He had some very real, highly significant achievements during his Presidency, things that shaped the world for decades afterward. This is all the more impressive in hindsight because he had to overcome some very significant obstacles, both by virtue of the time period and by dint of his personality and background.

To top it off, his enemies were very real, some of them were quite powerful, and many of them personified political and personal hypocrisy, particularly former Kennedy and Johnson era officials who were as guilty as anybody in creating a national environment where Watergate could take place. Freud's saying on how even paranoids have enemies definitely applies to Nixon.

But he was not a good President. Why? A fair amount of reasons, one of them being that he lacked the ability to make men see beyond themselves, to transcend themselves and "see the stars". He insistently swatted at enemies, real and imagined, creating more enemies than he needed to. For every one incorrigible Nixon hater who would have rather have seen the nation suffer than Nixon succeed, there were two people who may not have liked Nixon, but would have dealt with him out of respect for the office, particularly in Congress. However, Nixon alienated them rather than courted them. He treated a lot of talented people in government shabbily because of this. Nixon also wanted to rule as a Gaullist figure in American politics. While there isn't anything morally wrong per se with that, he should have known that this was something that in the long run wasn't compatible with American culture, particularly in that time era. He also lacked something fundamental-"character"-by 1972.

If it were merely those flaws, though, he would have been a good, solid President, just not one of the greats. Bush Senior couldn't make men see the stars. Clinton wasn't exactly known for his character. Yet both tend to get higher ratings than Nixon. Nixon's failings stemmed beyond that. He chose to misuse all those gifts for premeditated, malicious things as well as good ones, and that culminated in Watergate. Iran-Contra was extremely stupid and deserved censure, but Reagan honestly believed it to be part of the global fight against an admittedly evil ideology. The Lewinsky Scandal was extremely stupid and deserved censure, but in the sense of Dante Alighieri, it merely represented a personal lack of control on Clinton's part rather than premeditated conspiracy. So, in a way, Watergate eclipses those, both in the offense and in the effect it had on the nation, due in part to Nixon's personality. Nixon's insistence on fighting throughout Watergate came at a time where the nation did not need that, in so many ways.

His legacy will always start with Watergate and resignation. No way around that. I think as time goes on and those with an emotional stake in hating Nixon die off, he won't usually be on the bottom tier of Presidents along with the likes of Buchanan or Harding, but there is always going to be a very strong glass ceiling.