Depends how you defined disagreeable. Personally, I don't think so, but some people think curmudgeonly scholarly types are disagreeable. I don't. He knew what he liked and didn't mince words about what he didn't. For example, he didn't think much of the Narnia stories, telling CS Lewis "it won't do at all". CS Lewis, by contrast, praised The Lord of the Rings to the hilt (they were good friends, by the way, and Tolkien was responsible for converting CS Lewis, then an atheist, to Christianity).

However, if by disagreeable you mean he was racist, I don't think so. There is considerable evidence he was quite the opposite. For example, in 1938 when given the opportunity to have a German version of The Hobbit published in Nazi Germany, he declined, as it meant he had to sign a piece of paper declaring he wasn't Jewish. Instead, he told his publisher Stanley Unwin a German version could "go hang", also calling Hitler a "ruddy little ignoramus":

"I must say the enclosed letter from Rütten and Loening is a bit stiff. Do I suffer this impertinence because of the possession of a German name, or do their lunatic laws require a certificate of ‘arisch’ origin from all persons of all countries?

Personally I should be inclined to refuse to give any Bestätigung [confirmation] (although it happens that I can), and let a German translation go hang. In any case I should object strongly to any such declaration appearing in print. I do not regard the (probable) absence of all Jewish blood as necessarily honourable; and I have many Jewish friends, and should regret giving any colour to the notion that I subscribed to the wholly pernicious and unscientific race-doctrine."

This is the response he ultimately sent to the German publisher; a superb bit of anti-Nazi trolling, delivered with English courtesy:

" 25 July 1938

20 Northmoor Road, Oxford

Dear Sirs,

Thank you for your letter. I regret that I am not clear as to what you intend by arisch. I am not of Aryan extraction: that is Indo-Iranian; as far as I am aware none of my ancestors spoke Hindustani, Persian, Gypsy, or any related dialects. But if I am to understand that you are enquiring whether I am of Jewish origin, I can only reply that I regret that I appear to have no ancestors of that gifted people. My great-great-grandfather came to England in the eighteenth century from Germany: the main part of my descent is therefore purely English, and I am an English subject — which should be sufficient. I have been accustomed, nonetheless, to regard my German name with pride, and continued to do so throughout the period of the late regrettable war, in which I served in the English army. I cannot, however, forbear to comment that if impertinent and irrelevant inquiries of this sort are to become the rule in matters of literature, then the time is not far distant when a German name will no longer be a source of pride.

Your enquiry is doubtless made in order to comply with the laws of your own country, but that this should be held to apply to the subjects of another state would be improper, even if it had (as it has not) any bearing whatsoever on the merits of my work or its sustainability for publication, of which you appear to have satisfied yourselves without reference to my Abstammung.

I trust you will find this reply satisfactory, and

remain yours faithfully,

J. R. R. Tolkien"