How bad is it? Liberace stars and never appeared in another film because of its poor reception.
Should you see it? If you're a fan of Lee's.
Liberace plays a pianist who slowly goes blind. There's dozens of piano performances (I think 32 of them) in 116 minutes, padding a ten minute story mercilessly. The best thing I can say about it is that he plays a straight man rather believably, which seems unlikely if all you know is his stage persona.