In 2008, Doctor Who reached its fourth season under the leadership of Russell T. Davies. This was his final full length season, one written as a testament to the past three years. Catherine Tate reprised her role as Donna Noble, a middle aged woman with an attitude that had a place in the universe far beyond the obvious. While the general strengths and weaknesses inherent to Davies' run on Doctor Who are present, I would consider this to be the overall best season from 2005 to the present.
Donna Noble is a different kind of companion for new Who. She has no romantic interest in the Doctor, nor does she look up to him as a hero or a teacher. In fact, she's the kind of person week who has trouble being respectful to her boss. Donna stands with the Doctor as an equal and a friend. She also struggles with self-fulfilling self esteem issues: she treats every one the way she feels about herself, and gets crap back from life at the same time. Apart from her grandfather, the Doctor is probably the first person in Donna's life to treat her as though she's important, which is what sparks her character growth and ultimately makes the manner in which she leaves the TARDIS so devastating.
I've found that the best way to look at a season's strengths in this era is by the way each episode ties in to the finale. Series 4 is littered with several themes: Donna is important, she has no faith in herself, and something terrible is going to happen to her. There are also a few references to something invisible on Donna's back, referencing the penultimate story of this season in a Doctor Who version of "It's a Wonderful Life". And finally, almost every episode of this season features a missing world, or a moon. Sometimes it’s just an off-hand reference (running into a scholar who is looking for the Lost Moon of Poosh in “Midnight”) and sometimes it’s the catalyst of an episode (the disappearance of Adipose 4 in “Partners in Crime”).
As for more subtle connections between episodes, this season has more companions than ever. Two companions who would appear in future episodes feature in this season: newcomer River Song, and returning actor Bernard Cribbins reprises his role from Voyage of the Damned as Wilfred Mott, Donna’s grandfather. Billie Piper as Rose Tyler has several short cameos throughout the season, and Freema Agyeman appears as guest star in several episodes as Martha Jones. Finally, in “The Doctor’s Daughter”, the Doctor, Donna and Martha are joined by Jenny, a genetically modified clone of the Doctor played by Georgia Moffett, the daughter of Fifth Doctor Peter Davison (formerly Moffett) and future wife of David Tennant. I think future head writer Steven Moffat took notes on this relationship when planning Series 6.
This all leads up to the two-parter “The Stolen Earth” and “Journey’s End”, arguably my favorite Doctor Who story to date. This isn’t the most imaginative or thought-provoking episode, but Doctor Who doesn’t always need that. “Journey’s End” is about a long-time DW fanboy writing a special about his favorite villains doing their best to destroy the Doctor and his favorite people. Rose and Jackie Tyler, Mickey Smith, Jack Harkness, Sarah Jane Smith, Martha Jones and Donna Noble stand beside the Doctor as he faces off against Dalek creator Davros, while Wilf, Ianto Jones and Gwen Cooper from Torchwood, and Mr. Smith and Luke from Sarah Jane Adventures defend against the Daleks at home. K-9 and the Doctor’s hand from “Christmas Invasion” help deal with the crises at the end of the episode as well. "Journey’s End" wasn’t the last thing Russell T. Davies did for Doctor Who, but it was the end of the journey. Most of these individuals would continue to appear- Torchwood would run for two more seasons and each of the Doctor Who companions would appear in Davies’ final episode, but the end of Series 4 is the end of an era, and with a conclusion like this it’s only right that it’s the final complete season that he wrote for the show.
Barring "Journey’s End", Series 4 doesn’t have as many of my favorite moments as the earlier seasons did, but there’s also a lot less reasons to be squeamish of this season. I’d gladly take a few “Sontaran Strategem”’s in place of the combination of “Fear Her” and “The Impossible Planet”, or “The Doctor’s Daughter” in place of “Evolution of the Daleks”. That, and I just can’t help from watching the three episodes at the end of the season literally any time.
For a fair review, I need to admit that there are some faults here. Davros’s appearance is completely out of the blue. Despite the fact that 2005-2008 features more Daleks than any similar time period since 1975, there was never so much as a hint of his existence (unless you count the Doctor’s crack in “Evolution of the Daleks”). There really was never so much as a hint that Daleks had anything to do with anything that was going on, which makes the fact that the entire season leads up to them feel slightly off. On top of that, Donna starts off as a pretty annoying companion until she spends some time with the Doctor, and Rose and River’s reactions to Donna all but scream “ZOMG WATCH THE FINALE DONNA WON’T BE HERE NEXT SEASON!” Still, overall I feel these are rather minor drawbacks for such a solid season.