I've been a fan of Les Mis for many years and own 7 cast recordings in 3 languages. This is not a perfect recording, but it is very good and I was pleasantly surprised by it.
It is a live recording, which I feel is less sterile than a studio recording, but some might be distracted by the enthusiastic audience and the slight distant quality that comes with it. It's also the only recording in English with the post-1997 changes and the new orchestrations (of which I am a fan, myself).
In terms of the cast, John Owen-Jones alone is worth the price of admission. The man is a legend and this is the only legal recording of his Valjean available. He lives up to the reputation.
Katie Hall's Cosette has a very sweet voice, and is never shrill, unlike in some other recordings. Cosette is a difficult character to make likable, but she is lovely here.
Gareth Gates (Marius) is the big surprise in this album for me. He is not Michael Ball, but he is a capable singer and a good fit for Marius, definitely a better fit than Nick Jonas was in the 25th anniversary concert. He comes off as very young and naive, and I find him endearing.
Earl Carpenter starts off as a good Javert, not standing out particularly, but not completely botching it. Then he gets to the barricade, gets angry, and I love him to bits.
The ensemble, Les Amis de l'ABC in particular, are all very enthusiastic and really shine.
The Bad and the Boring:
Madalena Alberto as Fantine and Rosalind James as Eponine have very "pop" voices and a tendency to slide their notes. James in particular just sounds out of place in this sort of musical and makes some odd choices in emphasis. Alberto is still a decent Fantine, but James is one my least favourite Eponines.
Ashley Artus as Thenardier has a very gravelly, serious Thenardier, which isn't inherently bad, but he has little charm. Lynn Wilmot as Mme Thenardier doesn't stand out particularly.
Jon Robyns as Enjolras simply doesn't have that commanding quality in his voice that Enjolras requires. There are moments when he grasps it for a moment, then has to belt a high note and it is lost.
This is not the definitive Les Miserables, but it is a good album with a strong cast (for the most part) and I can recommend it to both new fans and veterans. If you only want one recording, I'd instead go for the 1995 Tenth Anniversary Concert, but if you want to try something different (or you want the wonderful John Owen-Jones), this recording is very, very good.