Don't get me wrong I actually really enjoyed the first five seasons; the writing was great, the special effects were really good, the atmosphere was close to perfect and the acting was, for the most part, very good.
But when the creator Eric Kripke stepped down at the end of the fifth season, the show started to slowly get worse. All of the special effects became computer generated (which looked a lot worse then the practical effects used in the first five seasons), the supporting actors began to get really annoying and the writing is a lot worse than it used to be; for example in the eighth season when Dean tackles Sam and tests if he is a leviathan etc. Sam doesn't seem very surprised to see his brother, who to his knowledge was dead, and speaking of bad writing I think it could have been much more entertaining if Dean had remained in Purgatory for the majority of the season.
In conclusion the first five seasons were really entertaining and I thoroughly enjoyed them but because Kripke stepped down the sixth season was pretty bad, the seventh season was quite awful and the eighth season is almost unwatchable.
But when the creator Eric Kripke stepped down at the end of the fifth season, the show started to slowly get worse. All of the special effects became computer generated (which looked a lot worse then the practical effects used in the first five seasons), the supporting actors began to get really annoying and the writing is a lot worse than it used to be; for example in the eighth season when Dean tackles Sam and tests if he is a leviathan etc. Sam doesn't seem very surprised to see his brother, who to his knowledge was dead, and speaking of bad writing I think it could have been much more entertaining if Dean had remained in Purgatory for the majority of the season.
In conclusion the first five seasons were really entertaining and I thoroughly enjoyed them but because Kripke stepped down the sixth season was pretty bad, the seventh season was quite awful and the eighth season is almost unwatchable.