After hearing 'Revolver' and subsequently changing my life, I thought these four couldn't get any better or cleverer. That is until I heard 'Rain', a song I'd been dying to hear. It is mind-blowing - great drumming from Ringo, superb harmonies from the other three, and strange lyrics. Then, as the drumming and bass stops, it plays backwards and their voices are so weird. Worth the listen.
As for the others, there's 'Revolution' - more famous than 'Rain' as a B-side to 'Hey Jude'. A rock number, it is brilliant. Another good track is George's 'Old Brown Shoe' - a pacy tune with an amazing bass line. His other song 'The Inner Light' has a beautiful Indian harmony and has clever lyrics.
If you own the 1 album, then I recommend you skip the singles you have to get more used to the others, especially 'You Know My Name'. I swear Rowley Birkin QC from 'The Fast Show' was created from John's grumbled voice at the end. This comedy song had me in stitches after hearing Dennis O'Bell sing.
Overall, this is a must for every Beatles fan. And 'Rain' is quality!