Set back from the quayside behind a tree, the building looks as though it's trying to efface itself. At first glance it looks like a simple cube of glass and metal framed by an L-shaped perimeter wall built almost entirely of aluminium sheet. Is that all?

By comparison with a few recent sensational L and XL projects from Koolhaas, the embassy is downright modest and subtle. It can, perhaps, be best considered an essay in choreography. Particularly impressive is the way in which passers-by, embassy officials and the city interact with one another. Nowhere is this more apparent than along the now-famous trajectory. This continuous promenade rises from street level to the rooftop. Though accessed is limited - this is an embassy after all - it's a feast for the senses, for diplomats and guests at least.

The route changes character as it rises: from steep stairs to gentle ramp, from dark and narrow corridor to fully glazed passageway attached to the building's exterior. It offers alternating views of the city outside and the workspaces inside. Before you realise it you've ascended the full 25 metres. Embassy officials rarely take the lift apparently, and they're right.

The irregular route and the complex spaces it carves out for offices make it a nightmare building for conventionally thinking people. It offers what you might call a sense of adventurous disorganisation. You almost expect to find Lara Croft or Dr. Spock lurking around every corner. But it's the perfect setting for establishing new channels of communication within an organisation and allowing colleagues from different departments to meet one another.

The use of materials is extremely subdued. Aluminium, steel and glass are used throughout and reinforce that Starship Enterprise feeling, especially along the promenade. Only in a few representative spaces have materials like dark wood and a splendid travertine with a wood-like grain been applied. And then there's the OMA habit of juxtaposing expensive and cheap materials. But the often-cited 'dirty realism' by Koolhaas is kept within limits. Not everything has been finished to precision of course. The sheet material in the courtyard, for example, looks as though it was cut with a pair of scissors, and a blunt one at that. Careful attention to detailing is mainly reserved for the interior, and that makes this a truly German building. It may be an enclave on foreign soil, but the embassy has to meet local building regulations. A number of loose ends therefore need to be resolved over the coming months. After all, the building isn't finished yet, and Queen isn't due until March.

Whereas the cube of embassy offices plays a virtuoso performance, the narrow slab that borders two sides of the courtyard and contains three apartments and some utilitarian spaces is of inferior quality. The street entrance to the apartments in particular is a travesty. Many a parking garage has a better entrance. And the long, narrow spaces in the apartments won't appeal to every embassy official. What a pity that it lacks the cast-iron concept applied elsewhere.

The exhibition CONTENT in the Neue Nationalgalerie has spawned a veritable Koolhaas boom in Germany. Newspapers are full of exhibition reviews and interviews, and the embassy is the focus of attention of course. The German press has been generally lyrical about the building. The Frankfurter Allegemeine comments that it's 'the most exciting and unconventional building built for a long time in Berlin'. The Süddeutshce Zeitung: 'Koolhaas has catapulted Berlin into the 21st century with this building'. Berliner Zeitung: 'This building is a communication machine'.

The only dissenting voice is that of conservative critic Rainer Haubrich in Die Welt. Highlighting the building's technical flaws, he writes that 'in many places you'd think the Dutch diplomats themselves have slapped the building together'.