He was always going to grow up but somehow when he does you feel a little nostalgic for sweet, innocent, little boy-wizard Harry. Only for a few fleeting moments, though: there's too much going on with the characters for you to stay bogged down in sentiment.

'Harry Potter and the Half-Blood Prince' sees Harry, Ron and Hermoine back together again but this time it's not so much a case of the three musketeers against the world, there's room for love interests, new friends and, of course, old enemies.

Professor Horace Slughorn (Broadbent) has been convinced by Dumbledore (Gambon) to return to his post at Hogwarts but, as Harry soon finds out, there's more to this appointment than meets the eye and he must use all his charm to get the answers that he and Dumbledore are looking for, particularly about Tom Riddle's curious years at the school.

In order to get closer to Slughorn and the answers, Harry must enlist in potions classes with Ron and Hermoine. Coming by a text book that once belonged to the Half-Blood Prince, Harry sails through lessons, developing a curiosity for the former owner of the book and learning a few new tricks to get him out of the sticky situations he so likes to get into.

Watch an interview with stars Evanna Lynch and Matt Lewis.

So far so good in terms of expectations for magic and intrigue. And then to the romances that dominate most of this film, when we really see Harry, Ron and Hermoine as adolescents struggling with their feelings about growing up and each other, and tackling heartbreak, excitement and crushing reality, especially when faced with the attentions of Lavender (Cave), Ginny (Wright) and several other admirers, intent on cooking up love potions and playing dirty in the flirting game. And, of course, there's the return of Draco Malfoy (Felton) to stir things up and Luna (Lynch) to act as a kind of dreamy fairy saviour, in that charming, other-worldly way that she does.

If this sounds like a lot of character action, that's because it is. 'Half- Blood Prince' is all about relationships, not just those of hormonal teenagers experiencing lust and jealously but also about relationships of trust and mutual admiration, like that of Harry and Dumbledore. At first it feels like you might be forced to like this movie less for its focus on people over spectacle but that soon becomes its charm. There's a tenderness about the proceedings that really comes across to the viewer for most of the film, with the climactic moments only slightly let down by the lack of fanfare.

'Half-Blood Prince' is an altogether more grown-up experience. If you go to see these movies because you love the special effects and wizardry alone then you might feel a little bit empty leaving the cinema, but if you're the kind of Potter fan who loves the characters you'll really appreciate where they go in this one, regardless of how sensational or dramatic that journey is. The success of this instalment lies in its ability to make you engage with the protagonists more, root for them (in love and adventure) and empathise with their pain.

Sometimes less is more.

Linda McGee