This "overrated"/"underrated" is a purely subjective discussion. Over/under rated just means you like it more than (you fill in the blank). If you love something and don't think there is anything better, there is no way it is overrated. Rated against what? I love all of the Beatles albums like children, I love them all for their own special qualities. Are there some I prefer more, yes. Even the ones that I feel are my least favorites still are not over/under-rated.
It might be, "Does... get more attention than you would give it?" I recently was involved in a discussion, in another forum, about 'Pet Sounds'. The polarization in feelings about 'Pet Sounds' is amazing. If you take a group of music enthusiasts and talk about 'Sgt Pepper' you will get different opinions. Some say that it is the greatest, and some will say that it is over hyped.
As has been stated 'Rubber Soul' is high on many fans list of favorite albums. It used to be my favorite, or shall I say most preferred. Now, I prefer 'Revolver' over 'Rubber Soul'. This does not mean that I think 'Revolver' is better. It just speaks to me more as to where I am in my life right now. We all could debate how "over/under-rated" an album is until we are all old and gray, and still not have an answer.
'Rubber Soul' is a great album. It gets lots of play time in my house. Underrated? That depends on who you are talking to.