Doctor Who is a bit of a guilty pleasure – it’s science-fiction in the “trappings” sense only: there’s technobabble and outer space locations, and “science” is just a way of justifying what needs to happen next for the storyline.
I saw the seasons out of order: the third, then the first, then the second. After seeing Tennant, Eccleston’s big friendly giant felt awkward and out of place.
The first season contained a lot of goofy episodes (pick any one with the Slitheen, or the one with the futuristic UK gameshows), but there were also some good ones: Father’s Day was poignant if predictable, and The Empty Child was Steven Moffat’s trademark excellent period sci-fi horror. I felt that the major arc was kind of cobbled together: while it used elements raised before, the storyline of the finale was rushed and underdeveloped.
The second season was a marked improvement, both with my acceptance of Tennant (who carries off the Doctor’s annoying preachiness and hypocrisy better) and the increased coherence of a season-long plot (the founding and mentions of Torchwood, the Cybermen). Additionally, the individual episodes were much stronger: School Reunion cast a hard look at the Doctor’s companion-churning ways, The Girl in the Fireplace was more Moffat goodness, and I really enjoyed the science-meets-religion The Impossible Planet and The Satan Pit. Even the Doctor’s shabby treatment of Mickey gets a spotlight (“I’m the tin dog!”).
Season three contained Moffat’s fantastic trio of Human Nature, The Family of Blood, and perhaps the best episode ever, Blink. However the finale did feel once against rushed together, with insufficient foreshadowing and groundwork.