I can understand why you wouldn't like Barry Lyndon: it is slow, and fixated on a very idiosyncratic corner of history/lit history. I think this comes down to a matter of personal taste, some people don't enjoy spending time with the characters and the places on screen here, and some people do.
With regards to 'omniscient narrator', I agree it is almost always ill suited to film, but for me in Barry Lyndon the world was so indebted to that of the novel, that the narrator didn't seem odd or out of place.
At the same time, I think anyone would be hard pressed to argue that the film isn't a landmark, technical achievement. I can't think of another film which looks like a moving 18th century painting. The film is also, consciously, epic, dealing with a wide spread of characters, locations and lives, fitting them into a framework which at the very least attempts to say something about 'the big things' (mortality, love, society etc etc). Even if it seems pretentious and vapid to some, it doesn't to others. It also feels singular (though so does all of Kubrick). I would be willing to bet you could take any frame and it would be recognizable out of context.
I actually think Barry Lyndon has aged better than 2001 and Dr. Strangelove, and maybe that's why it receives more love now than back when it was released. Barry Lyndon and the Shining don't have any special effects which look laughable in a modern context (men in ape costumes, psychedelic colours, falling against a greenscreen backdrop etc). 2001 and Dr. Strangelove are still immensely enjoyable, and valuable, and it's remarkable they haven't aged worse, but they still look like they were made when they were.
Sorry for being a pompous arse, I actually can really see where you're coming from, just trying to argue the other side :)