He played a good roll in the space program and civil rights, but is often blamed for the Vietnam War, which I feel he did not want, nor could stop.

As someone who studies the Vietnam War, I have decidedly mixed feelings toward Lyndon Johnson. Here's why:

You are correct that Johnson did not want to go to war in Vietnam. He understood, from a fairly early point in his presidency, that the war would be very difficult to win. And yet he escalated American involvement there. Figuring out why he did that is the million-dollar question for historians of the war, but most agree that while LBJ's options were limited, he probably did not have to send hundreds of thousands of ground troops and begin a massive carpet-bombing campaign of Northern Vietnam.

Johnson was, above all, obsessed with protecting what he saw as American "credibility." He, and his advisers, tended to conflate national credibility with personal credibility. They thought that if America's reputation as a guarantor against communist aggression were called into question, their careers would suffer. Johnson in particular was concerned that if he was perceived as not holding the line against communist aggression in Southeast Asia, he might be perceived as insufficiently manly, which could spell doom for his career, and his domestic initiatives in particular. I went into a bit more detail about why he thought this way in this post from a few months ago.

Presidents Eisenhower and Kennedy had ramped up American involvement in South Vietnam such that Johnson could not withdraw easily. Kennedy authorized a coup-de-etat three weeks before he died in which a group of dissident generals overthrew and assassinated the ruling President of South (the Republic of) Vietnam (or RVN), Ngo Dinh Diem. The political situation in the RVN, which had been tenuous before the coup, became much worse afterward, and the US had to assume more responsibility for the RVN's governance. America's willingness to greenlight Diem's overthrow showed how deeply involved the US was in the first place. So Johnson couldn't just leave without some form of controversy, and he was petrified of provoking the anti-communist right. But he also knew that most Americans did not want the US to become involved in a major war. And he did not want to provoke China. So he did his best to keep the war limited by confining US troops to the RVN and not calling up the US Army Reserves. The problem here is that for North Vietnam (the Democratic Republic of Vietnam, or DRV), it was a total war, not a limited one. Hanoi was generally willing to do whatever it took to win. Part of that meant using Laos and Cambodia as safe areas, since the US troops were forbidden from going there. It also meant using mass conscription, meaning that no matter how many enemy troops the US forces killed, there were more to replace them. Johnson chose to keep the war limited. He allowed domestic political imperatives to dictate how the US fought. And in the end, he chose war. Historians try not to engage in counterfactual thinking, but I'm confident that LBJ was a skilled enough politician that he could have figured out alternatives to his Vietnam policies that would have allowed him to save face. He may not have wanted the war, but he did not try hard enough to stop it. And that is why I, along with many other historians, have mixed feelings on Lyndon Baines Johnson.

I recommend that you read Fredrik Logevall's work Choosing War, as well as Robert Caro's multi-volume bio of LBJ.