I have had it a few times but not for years. The first time I had it the stuff was amazing, really really subtle. The following batches were no better than Kenco. It's about £100 a kilo and not many places sell it, which might give an indication as to the availability of decent stuff. I think most of it goes to Japan.
If I wanted something similar at non-silly prices I'd go for the stuff coming out of Papua New Guinea
Never tried it as espresso, but don't see any reason why not, apart from price