I like all 5 seasons - not so much to complain about, if you are fan of that genre and format. Very cozy sci-fi show in TV theater fashion with solid multilayer symbolic meaning, campy action, bold plot twists and simple moral messages. I call this sub genre "Second Wave Invasion" (Aliens don't hide themselves). Many viewers say that Season 2, 3 and 4 don't have the same intellectual level as Season 1. I disagree. First of all, it's TV fiction - my imagination is strong enough to fix any plot hole, and my political background is big enough to understand what was hidden from the casual viewer. Plus, I always assume that I don't have the full data about fictional situation. Second, there are pretty witty and smart episodes in Season 3. For example. Episode 2, when Liam framed Sandoval's blond girl agent. It was great to see stone cold Sandoval being hit with his own weapon. Final episode of Season 3 is pretty interesting too. As a russian I'm glad that our secret "Free Republic of Rostok" owns the Antarctica at last!)) Of course the style of the show makes some things look unrealistic, but political kitchen is well done. I start to get used to budget limitations and primitivism (in a good way), but then goes unexpected episode that shines with very "true to life" modern day conspiracy and tasty special effects. Some people even tried to convince me that Seasons 2-3-4 are not worthy of my "precious" time. Well, they were wrong in my case. I wasted my time on way way more useless things like Elections, Goverment serving, Casino playing and etc. I don't see any point of watching Season 1 without following the Taelon's mistery till the end. The story goes on giving the fuel for my endless curiosity. Season 4 was great in my opinion. Absolute majority of viewers say: "Whatever you think of Seasons 2-4, you should Fear the Season 5! It's not Earth-Final-Conflict anymore, but Buffy-The-Vampire-Slayer!" I will wait and see. I have nothing against Buffy, so I may like it. Let it be Buffy The Vampire Slayer then! Based on my current experience (Season 1-4), I give it 10 out of 10 (as I always do with watchable sci-fi movies and series). This litle medium budget sci-fi show has fantastic smooth designs, beautiful music, topical conspiracy themes about corruption, Invasion, LGBT, religion and etc. I'm hetero sexual earthling and I find nothing bad in Aliens being hermaphrodites, Aliens being good, bad and ugly. It's not SG-1, not enough humour and scale. It's not DS9/Voyager, not so epic and dramatic. It's in the field of Alien Nation, original V, Sliders and Seaquest. Watch it only when you finish the big shows.
P. S. Many people say Earth Final Conflict needs remake. I disagree once more. This show is Perfect in it's pleasant averageness. You can't reproduce it. It was done before 9/11 during the last golden era. It breathes 90s cable sci-fi aesthetic. And don't forget unique girls who played Taelons! Leni Parker and Anita La Selva - they did phenomenal job. Other actors were very good too. How can you "remake" them? I am strongly against remake in this case. Continuation is what I like in most cases.
UPD. At last, I have watched Season 5. I understand the confusion of many viewrs. It was like a shadow of the previous seasons filled with melancholia and withering. I believe - it was the point. It is the Final Conflict. When you are alone, and you struggle with yourself refusing to face your fate. Aside from philosophy there were some couple fun episodes, for example, I enjoyed the time travel and erotic romantic themes. I will borrow all 5 seasons on DVDs, it is nice peace of TV sci-fi history, in my opinion, and worthy of saving. No doubt, it would be censored or taken down for political reasons in the future.