Depends which fans you ask mate, I bet there aren't many Barcelona fans keen on him after a certain night in the nou camp
Seriously though, I think outside Newcastle (where he will always be a legend) he probably wasn't one of the best foreign imports. Fact is he was only over here for 3 seasons and if I remember correctly scored something like 9 or 10 premier league goals.
He wasn't great to watch, and as I say, I'm a toon fan and I wont forget him in a hurry. Legend. One of the best? Not for me
Coming from Scotland and not going to English league games i can only base my answer on what i have seen on TV, usually a lot of highlights programmes. When i think of the really top foreign players it would be Bergkamp, Cantona, Zola, Klinsman, Ronaldo, Viera. I think Asprilla would certainly be well down the list of legends.