[Georgia Senator] Dick Russell is absolutely shittin’ a squealin’ worm. He thinks it’s a disgrace for a kid who’s never practiced law to be appointed...I agree with him.

-Vice President-elect Lyndon Johnson, 1960

When Jack Kennedy announced that his brother and former campaign manager Bobby (that's generally how writers refer to them, so, here we are) would serve as Attorney General, the public reaction was pretty much what they expected--which was to say, not ideal. Least of all from fellow Democrats.

According to Michael Beschloss, people wrote to the DNC in protest at a rate one hundred times what they mentioned in support. While we can count on the general principle of online reviews--upset people are the most motivated to leave comments--the scale of difference backs up information gleaned from interviews and letters with prominent government officials. Media reaction, too, was initially sharply against the appointment. After Jack floated the idea to a New York Times reporter well in advance of a formal arrangement being announced, the paper printed an editorial not quite as blistering as Johnson's version but nevertheless firm:

It is simply not good enough to name a bright young political manager, no matter how bright or how young or how personally loyal, to a major post in government that by rights (if not by precedent) ought to be kept completely out of the political arena.

There's something interesting about this sentiment, though. Nepotism doesn't even merit an explicit mention. The Times is first and foremost unhappy with Bobby's previous role as campaign manager and especially his inexperience:

If Robert Kennedy was one of the outstanding lawyers of the country, a preeminent legal philosopher, a noted prosecutor or legal officer at the Federal or State level, the situation would have been different.

The Wall Street Journal went on record with the same sentiment, suggesting such an inexperienced AG would be an "unqualified disaster."

Russell and Johnson above protested similarly--Bobby wasn't qualified to be AG based on his own (lack of) merits, quite independent of concerns whether he might not be the best of a set of qualified appointees just getting the job because Jack needed a right hand man.

A more interesting question is whether the appointment was/was ever controversial with Bobby. The Kennedy brothers certainly stage-managed it that way in the public eye. Jack did try to place several others in the AG role first, but they turned it down for reasons like not wanting to be a Jewish AG under a Catholic president trying to force civil rights legislation on a region that included a strong anti-Catholic, anti-Semitic, KKK or KKK-sympathizing element.

Notes taken by Jack's secretary, Evelyn Lincoln, right before the appointment was formally announced in December 1960 indicate a phone conversation between the brothers, in which Jack tried to get Bobby to accept a whole spectrum of government roles--electoral, Cabinet-level, White House staff--but the latter was having none of it. Any of it. ("Would rather write a book," Lincoln noted; "as an interim thing, maybe a college presidency," related William Douglas). There was even a rumor circulated by Jack's allies that Kennedy family patriarch Joseph had put his sons up to it. This rumor is especially noteworthy because it would likely stoke fears/charges of nepotism rather than calm them--inexperience, it seems, really was the biggest sticking point.

...But was it so for Bobby? In fact, his own record is somewhat ambivalent on the matter. Even as Lincoln was making notes of that phone conversation, Bobby wrote in a letter:

I made up my mind today and Jack and I take the plunge tomorrow. For many reasons I believe it was the only thing I could do--I shall do my best and hope that it turns out well.

He might also have been concerned about his lack of experience, and it seems from other comments he was worried that having to enforce civil rights laws would backfire on his brother's popularity if they were seen as too close. But in 1965, long after it should have been an issue of immediate importance, Bobby was back to asserting his initial reluctance. Truth? Or cagey political move with an eye towards an even greater government role?

Ultimately, of course, the calculation that an initial public and press outcry would quickly die down proved correct. But it absolutely did flare up in the first place.