Dutch Elm Conservatoire

The high-octane start to this sketch show is a false dawn.

The high-octane start to this sketch show is a false dawn. It is hard not to like the end product of five young men who act well, and who exude markedly different charisma despite all being dressed in black. In parts, there is a feel of Victorian macabre about it that is well suited to Edinburgh, like a more digestible Shockheaded Peter.

There are glimpses of potential in the mix of Monty Python meets Big Train sketches, but all too often situations are unfinished, laughter is left in suspension. A talking baby genius, a policeman who tries to end hostage situations by reciting recipes over a loudspeaker, a flashy magician, an argument between KFC's Colonel Sanders and the Little Chef hold momentary charm. But they soon exhaust their one-laugh quota. Meanwhile, an Animal Farm-style scenario chaired by the farmer, and a boy-band depiction of railway staff, have more potential.

If the tiny, throwaway sketches were thrown away, and the more lengthy sketches were worked on, the pacing of this show would still be fine. The problem with this troupe is not one of boredom, but of subtlety and a slight smugness. The punchlines are often of the "now you see it; now you don't" variety, when more in-yer-face attitude and pride are needed.

It is a rare act that unites audiences, critics and comedians. The bumbling banter and tightly constructed parody songs of Bret McKenzie and Jermaine Clement, aka Flight of the Conchords, in Lonely Knights, are just such an act. The eager anticipation of their return to the Fringe has only midly been dampened by the realisation that this show isn't as good as last year's. I found myself willing the pair on to bypass the inane chatter about imaginary children and get on with rolling out their tunes. As with the chat, some numbers proved to be a stream-of-consciousness work in progress. Nevertheless, pleasing couplets, unexpected climaxes and the a capella nonsense were not too far away. Crossing the musical universe from ballads to hip hop, the duo strike comedy poses and tease with lyrics such as "looking round the room, I could tell you were the most beautiful girl in the room", or "you're so beautiful, you could be a waitress."

The Reid Hall, which is normally a lecture theatre, is not the best venue at which to feel the subtlety of a lot of the Conchords' act, particularly if you are at the back. The raucous laughter of some audiences members felt disingenuous, straining for the laughs as one might strain an ear to listen to the music. That said, the Conchords do provide some lovely in-flight entertainment.

Dutch Elm Conservatoire, Pleasance Courtyard, to 30 August (0131-556 6550). Flight of the Conchords: Lonely Knights, Metro Gilded Balloon, Edinburgh, to 30 August (0131-668 1633)