Incredible game - currently bettered only by Dark Souls. It is difficult but the difficulty is surmountable with patience and some common sense. The game does not require the same level of sheer skill as, say, Street Fighter or GT5, but as you are often so hopelessly outmatched against normal enemies, let alone bosses, the satisfaction from completing just parts of each level is highly rewarding. Dark Souls offers a slightly different experience as the levels are more inter-connected and there's less portal-hopping but they are both excellent and well worth the full price, let alone the 10-15 pounds this one's now going for.
The only (minor) problem is the level of grinding if you're going for the platinum. Some items require either luck or tens of hours to obtain so this can be frustrating if you're not one of the lucky ones. This should in no way discourage you from buying and playing this. A lot.