Russell is generally rather petty throughout his History of Western Philosophy, though that doesn't necessarily mean he doesn't have a point. But I would say that that book is staggeringly outdated and very misleading in many respects, even on those where Russell was a true expert, such as Leibniz.
On Nietzsche, it really depends on what Russell means. Obviously Nietzsche was not a professional academic and did not have a university position, so it's true to say he wasn't academic in that sense - but that's no criticism, since the same thing could be said of any number of other major philosophers, including Descartes, Leibniz, Hume, and so on. Presumably Russell is commenting on Nietzsche's style, and there he surely does have a point, since Nietzsche doesn't write like an analytic philosopher but uses narrative, suggestion, rhetoric, and other literary devices. In fact he's an archetypal continental philosopher, at least in that regard. Of course there's always been much disagreement over how to interpret Nietzsche, and in particular whether he can be "made into" a canonical analytic-type philosopher - whether one can extract definite positions and arguments from his works, which could then be taught academically in the same way as those of other philosophers, or whether such an enterprise involves completely misunderstanding what he's doing. But I don't know nearly enough about Nietzsche to give a view on that.
