This is also the season that introduces Catherine Tate as full-time companion Donna Noble, working alongside David Tennant's Doctor across time and space. And it's--against initial expectations--arguably the best combination since the show returned. There's no hint of romance between the pair, as they instead knuckle down to business, occasionally helped by the likes of Martha Jones (Freema Agyeman), Sarah Jane Smith (Elisabeth Sladen), and Jack Harkness (John Barrowman). And let's not forget the collection of monsters we meet this time around. The Daleks and Davros are the main attractions, while the return of the Sontarans proves to be a bit of a disappointment. But after viewing the series, chances are you'll be counting shadows around you, and wary of getting on the wrong side of the Ood.
As with most series of Doctor Who, there are one or two uneven episodes and some missteps, but the show is still unmatched at what it does, and even more confident than last time round. That, along with the immense rewatch value, is what makes this a terrific piece of family entertainment.