I will forever love this show, it has had some of the best, heart-pounding scenes offered on modern televisions, there can be times when the show is slow, but never fails to entertain or deliver especially in the season finales and openings.
Season 1-2 are brilliant, slow, scary and really build the characters and apocalyptic world. The last two episodes in the season are fantastic.
Season 3-5 are also very good giving the survivors a more permanent location... but also an introduction to the threat of humans and their nature once civilization has collapsed, also this season features the biggest herd of walkers. The opening episode in season 5 is an amazing one.
Season 6 I would say is the best season from episode 1-9 it's almost non-stop action, from the moment it begins to the end you'll be on the edge of your seat, the latter half of the season introduces the worst threat to date; Episode 9 I would say is the best episode of the series so far.
Season 7-8 I daresay these episodes drag on, I no doubt enjoyed the show but a lot of people caved in during these seasons, there are still some amazing scenes, twists and great character developments if you can pump through it all.
Season 9 hasn't finished yet but the show is phenomenal again, it goes in a completely new and unexpected direction but I'm loving every minute of it, the new enemies are what they needed and a decent threat to the survivors.
All in all, I definitely recommend this show, one of the best on offer.