Fantastically long-running and popular, even in the dark days when there was no tv series. You do see a lot advertised for sale though, even early issues so pretty static in values. The early ones are most in demand with later David Tennant issues in demand also.
Free gift transfers with issue #1 are pretty common and you'd expect them to be part of the comic. They were attached to the front cover rather than loose inside so many copies on eBay UK have them attached as standard. In fact issues #2 and #3 had a free sheet of transfers and they're pretty common.
This is what Wikipedia has to say by way of more general information:
Doctor Who Magazine (abbreviated as DWM) is a magazine devoted to the long-running British science fiction television series Doctor Who. Its current editor is Tom Spilsbury. It is the current Guinness Book of World Records holder for the longest running TV Tie-in.
Officially sanctioned by the BBC, the magazine began life as Doctor Who Weekly in 1979, published by the UK arm of Marvel Comics. The first issue was released on Thursday 11 October with a cover date of 17 October and priced 12p.
The magazine moved from weekly to monthly publication with issue 44 in September 1980, becoming Doctor Who (the tagline "A Marvel Monthly" was not part of the name, but simply a description which appeared on many of Marvel UK's monthly titles at that point) and a cover price of 30p. The title changed to Doctor Who Monthly with issue 61 and The Official Doctor Who Magazine with issue 85 in February 1984. It became The Doctor Who Magazine with issue 99 in April 1985, and simply Doctor Who Magazine with issue 107 in December 1985. The magazine has remained under that title ever since, although an exception was made for issue 397 in June 2008 when the cover only featured the words Bad Wolf following transmission of the Doctor Who episode "Turn Left" on Saturday 21 June. In 1990 the magazine started appearing once every four weeks (13 times a year). Despite the BBC discontinuing production of Doctor Who in 1989, the magazine continued to be published, providing new adventures in the form of comics. The television programme was revived in 2005, providing a new generation of fans which the magazine was seeking to attract.
Originally geared towards children, DWM has grown into a more mature magazine exploring the behind-the-scenes aspects of the series.Due to its longevity, it is seen as a source of 'official' and exclusive information, sharing a close relationship with the television production team and the BBC. In 2006, however, it lost its exclusivity when BBC Worldwide launched its own comic, Doctor Who Adventures, aimed at a younger audience.
DWM is now published by Panini Comics, which purchased the title along with the rest of the Marvel UK catalogue in 1995. Panini has begun to digitally restore and reprint older DWM comics in trade paperback format. Twelve volumes have been printed so far: two featuring the comics adventures of the Fourth Doctor, one with the adventures of the Fifth Doctor, two featuring the Sixth Doctor, one with the adventures of the Seventh Doctor, four focusing on the Eighth Doctor, and two featuring the Tenth Doctor. Panini also published a one-shot magazine-format reprinting of the complete Ninth Doctor strips in 2006 and most of the Tenth Doctor and Martha Jones strips in 2008. DWM issue 426 reported that the series has been postponed, although Panini hopes to be able to continue it in the future.
DWM's 400th issue was published in September 2008, and the publication celebrated its 30th anniversary in October 2009. In April 2010, it was confirmed in issue 420 that Doctor Who Magazine now holds the Guinness World Record for "Longest Running Magazine Based on a Television Series."
Note: some PR issues may have no value. Selected issues in FN, VF or VF/NM may not exist in some titles.