Overated:BB5 (Don't shoot me!) The only reason people love it so much was because it came after the dreadful BB4. The tasks were average and to be fair the housemates did blend well together, the rivalry between the JCs and the LGBs was OK, the decor was horrid and a predetermined winner (Not that she didn't deserve to)
Underated: BB6 is my favourite series and the only reason that it is underated is because it came after the massivly overated BB5. Every twist worked perfectly E.G The Secret Garden, and was the series of secret missions (bring them back!). The morning after Poolgate if BB gold and every housemate provided something (even Orlaithe and Sam when at their best!).