The first runs from the mini-series to the end of 'Exodus Part II' and features one over-arcing narrative split into four separate arcs (the escape from the Colonies, Kobol, Pegasus and New Caprica) and is pretty much continuous awesome. The stories flow into one another and it feels like 'there is a plan'.

The second runs from 'Collaborators' to the mutiny trilogy and is the most unfocused part of the show, with lots of weird character decisions (what's Lee's next job going to be? What is Anders doing this week? Shall we keep Baltar in the 1970s Disco Basestar for a few more weeks?) and cheap melodrama weighing the story down. Tyrol and Cally's marriage problems and the Lee/Kara/Anders/Dee QUADRANGLE OF DOOM making every viewer want to kill all of the characters involved. The humour - albeit often black - that used to keep some levity in the show is gone and everything gets grim. The formerly exacting sttention to detail and continuity has gone out the window, and it's unclear what the Fleet's goal at this stage is.

Late in this period we find out who the Final Five are and discover that the artistic direction of the series is going to be decided by the whimsical musical choices of the head writer rather than character, logic or drama. Things go completely bonkers in early Season 4 with characters losing legs at random, dogs appearing and never being referenced again, the HALLUCI-CAT episode, Lee Adama getting insane promotions and demotions for no real reason and people distrusting the mysteriously-resurrected Starbuck until she goes nuts and holds people at gunpoint, at which point they give her a ship and tons of crew to go off on a mission. What?

At the end of this rollercoaster of surreality they have 'Revelations', which is actually brilliant. The ending is monstrously powerful. If the show had ended at that point it would still, despite the insanity of the last season, still be highly regarded and talked about for years to come. The fall-out from that through 'Sometimes a Great Notion' and the mutiny trilogy is also very well-handled.

Then there's the final run of episodes which are shockingly bad I'm surprised they were ever made. Galactica has been falling apart for four years and suddenly it's so bad the ship is going to blow up in a matter of weeks? And none of the hundreds of engineers or thousands of crewmen on the ship noticed? What? Hera is suddenly important again to the story despite being ignored for the past season and a half?

By the end of the series I was cringing in embarrassment at some of the dialogue and decisions being made on-screen. Some of the decisions made in the extremely bizarre finale are literally incomprehensible.

In conclusion, I think the series had a very strong opening 37 episodes and the mini-series, and then traded off the back of that for the rest of the series with no real plan.

The artistic failure of BSG (which did not have a pre-planned story arc) and the triumph of AVATAR: THE LAST AIRBENDER, BABYLON 5 and THE WIRE (all of which did) would, in a sane world, hopefully ensure that all future arc-based series are pre-planned. Some hope though, as the same writers are already laughing about making up CAPRICA as they go along.

Interesting to see how LOST - which they started off making up as they went along and then sat down and worked out 'a plan' early in Season 1 - ends and which side of the fence it will fall on.