Doctor Who: Matt Smith and Karen Gillan step out

Doctor Who fans have finally got their first glimpse of the new Time Lord Matt Smith and his companion Karen Gillan. The pair's debut episode was premiered at a launch party for the new series in Cardiff, where Doctor Who is filmed.

Entitled 'The Eleventh Hour', Smith's first full episode in the role shows him landing on earth and plummeting straight into a new alien threat - a shapeshifting monster called Prisoner Zero - while dealing with his own reincarnation. The Doctor and his new companion Amy Pond, played by Gillan, have just 20 minutes to save the world.

Smith was briefly seen at the very end of David Tennant's final outing as the Doctor, shown as a two-part special over Christmas. The fully regenerated Time Lord will make his television debut proper on BBC One at Easter, traditionally seen as the season for resurrection.  

The initial verdict on 27-year-old Smith, the youngest actor to land the part, is favourable. The Guardian's Daniel Martin described his performance as "commanding".

Meanwhile Gillan, 22, makes a memorable debut too - not least because she first appears as a kissogram, dressed in a short-skirted policewoman's uniform. As the Times' Andrew Billen noted, the presence of Gillan, as a "vivacious redhead", more than makes up "for the Doctor's relief last Christmas on discovering he is not ginger" - a throwaway quip that caused an outcry from certain viewers.

The new series also sees a change behind the scenes, with Steven Moffat taking over from Russell T Davies as executive producer and lead writer. As well as a new Doctor and companion, Moffat has brought in a cutting-edge HD shooting style, a new logo, remixed theme music and - most excitingly for fans - a new-look time machine.

The redesigned interior of the Tardis is vastly different to the previous one. At three levels, it is nearly twice the size of the previous one. The new console at its centre is an eccentric collection of objects including a typewriter, a 1980s touchphone, a gramophone speaker and a petrol pump.

The new series of Doctor Who starts on BBC One on April 3.WHAT THEY ARE SAYING:Daniel Martin, the Guardian: "[The new incarnation of the Doctor is] part preppy public-school head boy; part gung-ho adventurer and part 'nutty professor' – a boy-racer in geography-teacher elbow patches."

Andrew Billen, the Times: "Smith is undoubtedly aristocratic, a prince rather than a lord of space and time, but one in no doubt of his lineage."

Simon Brew, denofgeek.com: "Amy Pond is coming across as a strong companion, and one a little different to the last few travellers in the Tardis. And Karen Gillan is looking like a fine choice to play her."

Sky.com: "Any concern that Matt Smith might not be the man for the highest profile role in British telly are immediately dispelled as the actor injects a new energy and enthusiasm to the part, so lacking in the previous series." ·