When I first watched this show, I was not sure, the pilot was not that strong. However, after following it for a couple of episodes, I soon fell in love. James Spader depicts Reddington's character with subtle charm and erudite brilliance. I love the way Spader crafts his stories and speaks with profound eloquence and sophistication. I also applaud the complexity that this show maintains (with the exceptions of seasons 8 and 9), and how random sentences stated in season 4 one time can contain so much information revealed seasons ahead. The show was planned out in advance and everything ties together once you learn the truths.
You must be patient, though. Many secrets that were brought up in season 1 are not answered for 10 seasons. The supporting cast contains a lot of skill, and my favorite is Tom. Shame his spin-off never worked out. I personally like Liz, but I know a lot of people do not, and I understand why. She is constantly in a love-hate relationship with Reddington which can sometimes take away from the story. I would say that the first 6 seasons are the best series of episodes that I have ever watched. I hope one day that the show can match the complexity of season 2, the wit of season 1, the twists of season 3, the humor of season 6, the pathos of season 5, and the storytelling of season 4. Season 7 just felt like a waste in hindsight, season 8 was hurt by Liz's on-off screen times and boring blacklisters, and season 9 was hindered by repeated storylines, blown opportunities, and failed experiments (including my least favorite psychedelic groundhog's Day episode).
Overall, I strongly support and will see this show out to the end. I just hope that the show can regain its once brilliant composition.