Umu, London W1

I feel almost ill from spending money, and it is only 8.30pm. Kaiseki is one of the world's most expensive ways to eat; a finely choreographed, highly developed sequence of beautifully crafted, harmonious, highly seasonal small dishes designed to showcase the skills and aesthetics of the chef. Quite simply, it is Japanese cooking at its most refined, defined and designed.

I feel almost ill from spending money, and it is only 8.30pm. Kaiseki is one of the world's most expensive ways to eat; a finely choreographed, highly developed sequence of beautifully crafted, harmonious, highly seasonal small dishes designed to showcase the skills and aesthetics of the chef. Quite simply, it is Japanese cooking at its most refined, defined and designed.

The highest form of kaiseki hails from the ancient capital of Japan, Kyoto, so I was very excited about Umu, Britain's first Kyoto-style kaiseki restaurant. Umu was recently opened by the big-spending Marc group, which is clearly having fun playing Restaurant Monopoly, with two existing Mayfair properties in the Greenhouse and Morton's private members' club.

Adding to the appeal of Umu ("born of nature") is the fact that it is borne not of nature but of Taipei-born, New York-based designer Tony Chi. The façade is low-key and high security, but once inside, all is lush, lavish and indulgent. Dark, rich timbers gleam in the soft light, mirrors reflect velvet banquettes, and low-slung ice buckets look like nine-pin bowls. Even the sushi bar marooned between two dining-rooms has a sense of opulence, as does a softly glowing glass-fronted temperature-controlled wall of wine.

Basically, Umu is a padded asylum for the very rich. Executive chef, Ichiro Kubota, has put together what is in effect an à la carte kaiseki menu with dishes grouped under the various courses that make up a banquet - appetisers (tsukidashi), soups (suimono), raw fish (tsukuri), fried dishes (agemono), simmered dishes (takiawase), rice (gohan) and desserts (kashi). Then there is a menu of classic, modern and warm sushi at £3 to £6 per piece, as well as a separate specials menu. Ordering a "deconstructed kaiseki" from the à la carte is difficult and quite stressful, however, so most people skip straight to one of a number of set kaiseki courses with or without sushi that run from £70 to £240 per person.

The two of us do one £70 kaiseki course and put together six small courses in the vain hope it will flow into a harmonious meal. So far, I have paid £9 for a small, classy dish of simmered mackerel with brown miso, £7 for a messy salad of frisée and green-tea noodles in a sesame dressing, £9 for some chewy and insipid tempura duck rolls with Tokyo onion and £8 for a small bowl of bland, bland, bland oyster rice.

After hearing stories of how the indigenous Japanese vegetables and wild fish are being flown from Japan, and that the chef insists on cooking with specially imported Japanese water because London water is too harsh, I had been expecting a meal of breathtaking perfection. Instead, my breath is taken away by yawning, as dishes vary from the humdrum to the unexciting, with the odd digression into what-were-they-thinking? A tiny finger of very fresh sea- urchin sushi is a blast (at £6 a pop), and a dessert of custard set with kuzu starch has the familiar, appealing texture of blancmange but, by the end, I feel neither harmonious nor fed.

The two stand-out dishes appear in the kaiseki menu, with a sashimi plate of chu toro (middle tuna belly), langoustine and sea bream that makes me wonder why anyone would ever cook fish, served with grated fresh wasabi that is going to make me shed tears when I'm back on the powdered stuff.

Also special is a teriyaki of tuna belly with yuzu (sour Japanese citrus) which melts like butter in the mouth. Then, before you know it, along come a couple of not-so-special dishes, a very ordinary fruit platter, and it's all over bar the tummy rumbles.

I was initiated into kaiseki in Tokyo and in Uwajima, and I can't quite credit the lack of harmony and beauty in tonight's effort.

I can see the technique in walnut tofu with miso, appreciate the subtlety of sea bream with asparagus in a clear broth, and admire the authenticity of a red miso soup with wild mushrooms, but what they call subtle, I call bland. Worse, the hot fish dishes are over-cooked.

Umu is a very weird restaurant, in part luxurious and stimulating, and in part boring and difficult. The sake list is a doozy, but the vast wine list seems inappropriate to the food. Some of the staff are charming and helpful, others are clearly out of their depth.

Umu is Annabel's with added sushi, a may-as-well-be-private club for those who find Cipriani too fattening and Nobu too full of commoners. Above all, it is prohibitively expensive for all but the very rich, and the problem with that is that very rich people don't really care what they eat as long as they eat it in the company of other very rich people.

I like the reversible chopsticks, the luxurious interiors, the sashimi langoustine and tuna belly, and how my neighbour, having also ordered sashimi langoustine, poked it with a chopstick and said, "Eeeugh, raw fish".

But I don't think Umu is doing what people want, and it isn't doing what people don't want well enough to make them change their minds.

13 Umu 14-16 Bruton Place, London W1, tel: 020 7499 8881. Open for lunch and dinner Mon-Sat. Around £200 for dinner for two including wine and service

Scores 1-9 stay home and cook 10-11 needs help 12 ok 13 pleasant enough 14 good 15 very good 16 capable of greatness 17 special, can't wait to go back 18 highly honourable 19 unique and memorable 20 as good as it gets

Second helpings: Other (non-Kyoto-style) kaisekis

The Rosemary Restaurant Stanton House Hotel, The Avenue, Stanton Fitzwarren, Wiltshire, tel: 01793 861 777 This glorious Cotswold-stone manor house couldn't look more British if it tried, yet it is home to an extremely authentic Japanese restaurant, owned by the nearby Honda Kaihutsu company. There are bento lunchboxes and a Sunday buffet; while at night, there are three kaiseki menus from £30 to 50 each.

Mitsukoshi 14-20 Lower Regent Street, London SW1, tel: 020 7930 0317 When this popular restaurant opened near Piccadilly Circus nearly 20 years ago, it was one of London's first sushi strongholds, although the menu runs to everything from shabu shabu to sukiyaki. To get the full Mitsukoshi experience, try the eight-course "kisetu no kaiseki" menu for £30 or the chef's special kaiseki at £50.

Chino Latino Park Plaza Hotel, 41 Maid Marion Way, Nottingham, tel: 0115 947 7444 Chino Latino is a funky fusion of a Latin bar scene and modern, Japanese-driven dining. People who don't like missing out on anything should try one of the three set menus which can be ordered for groups of four or more. The top- of-the-range 10-course menu includes Nobu-inspired black cod, beef fillet in three sauces and jungle curry with lobster, shrimp and scallop.

E-mail Terry Durack about where you've eaten lately at t.durack@independent.co.uk