Okay first things first; if you're looking for a repeat of The Lion King, you won't find it here. The Lion King 2 is a sequel in the best sense of the word. It takes the story and characters of the first film and builds on them without being too afraid to step in another direction.
The constant references to Scar and the, um, 'scars', he has left may indeed turn some people off. Personally I loved it. Kiera and Kovu are worthy successors to Simba and Nala. Here we have characters who cannot escape the past, but unlike the first film where Simba is trying to escape HIS past, they are trapped in the shadow of events before their time. They weren't a part of Scar's betrayal or downfall yet they still live with the consequences. Their struggle to be seen as individuals away from their heritage is a metaphor that easily applies to the film as a whole and I for one think it is wholly successful.
The film is altogether darker than the first, (Scar's vengeful mate is a pretty twisted figure), but it works perfectly in it's context as a sequel. You watch The Lion King when you're young and fall in love with the beautiful artwork and songs, then you watch The Lion King 2 when you are a bit older and appreciate for the first time just how complex the first film was to leave such a legacy, and hopefully see it in a new light.
Some people won't want to view an old favourite in a new light, and I must admit I didn't watch this film out of choice, but the new characters soon had me involved in a whole new way, the new songs, (especially the emotional, 'He's Not One of Us'), are never far from my tongue, and in moments of doubt Timon and Pumba are there to ease you along.
There are many Disney sequels and most are straight-to-video for a reason, but if you dismiss The Lion King 2 on those principles, you'll miss out on a real gem.