I saw a 70mm print of the film last Halloween and had a blast. The visual effects haven't stood the test of time at all, though. It's a testament to how good the rest of the movie is that it's lasted.
Some hold up better than others. The neutron streams still look pretty great, as does basically everything in the climax. Even the Library Ghost looks pretty good, nowadays. Slimer, however, looks like utter ass
. Really, it's more a testament to how so much was done practically, as opposed to other methods.