Well, this is certainly interesting. Though Metal Gear Solid 4: Guns of the Patriots has been getting positively glowing reviews from many UK outlets, there seems to be an undercurrent of ... dissatisfaction among many in the reviewing community. Completely unsurprisingly, it seems that most of the high-90s/100s reviewers are hyperbolically positive. (They've been saving up their good writing all year!) Regardless, it seems that general consensus is that fans of the series are going to have a ball. Read on:
IGN(99/100): "If you've ever loved any one of the Metal Gear games, or any moments from the series, there will come a moment when MGS 4 will send your spirits soaring. If you've loved them all, well then there'll be many, many more. It's a masterpiece."
PSM3 UK(95/100): "Will you enjoy it? Yes, definitely, but while most hardcore fans will adore it, a tiny minority may be left slightly deflated by the weight of their expectations, despite the game's unarguable quality."
Edge Magazine(80/100): "MGS4 is not the game it could have been; nor is it the game it would have been had the series grown with the benefit of hindsight; nor is it the game it should have been if you believed that early trailer. But it is faithful to its fans, its premise and its heart, delivering an experience that is, in so many ways, without equal."