Film adaptations of books are always a melting pot of opinions and all too often the opinion most resistant to melting is that justice has not been done.  So is "The Hitch Hikers Guide To The Galaxy" another culprit to add to the list?

Disappointingly, although not said without some reservation, the answer is yes.  The question of why is what poses a problem. The elements that usually harm an adaptation such as this all seem to have been addressed.

Let's start with the cast. Ok, so maybe Arthur is a little young, Trillian is American and most readers would never have imagined Mos Def in the role of Ford Prefect, but they do all bring something positive to their roles and any niggles are generally minor ones that soon dissipate.  The supporting cast also appear well chosen.  Sam Rockwell brings the expected crazy-coolness to Zaphod, while Bill Nighy and Alan Rickman, as Slartibartfast and the voice of Marvin respectively, are particular highlights.

So if it's not the cast it must be the visualisation of it?  All too often you read a book and your own imagination is hideously undercut when the page transfers to the screen. No, not that either.  The sets look great, the Jim Henson workshop has done a fantastic job of the various aliens and the overall presentation and effects are hard to fault.

Right, so it's not the cast, it's not the visualisation or the effects. Must be the humour? Getting warmer, but not quite there.  The movie has its fair share of laughs, and with the source material there would really be no excuse for it not to.  The problem lies in the pacing and the film never feels as though it really gets going, resulting in a twinge of "was that it?" as the end-credits roll over a somewhat lack-lustre finale.

Much of what made the books and radio series so great is possibly lying on a cutting room floor somewhere and die-hard fans may find themselves unfulfilled by a script that on a number of occasions builds up to a moment of Adams genius, only to flop to the next scene before it's delivered.

Despite the obligitory romantic sub-plot and some dumbing down for a... ahem... "world-wide" audience, it is a reasonably enjoyable hour and a half, albeit a chapter in the Hitch Hikers saga that serves more as a reminder of how good the originals were, rather than as an addition to their greatness.