Harry Enfield and Paul Whitehouse's reunion a few years back was exciting, but also left many people asking one question - could they reproduce the material that saw them, along with Kathy Burke, define sketch show comedy in the 1990s? To many people's surprise they proved they were still capable of creating some fantastic characters, like the posh builders, and last year the second series garnered a Bafta.

With the start of their third series tonight, we hope we haven't already passed the high point of their reunion, because while this does feature plenty of understated chuckles, it rarely leaves you breathless from laughing. However, there are some ingenious ideas, including an 'original' 1930's version of When Harry Met Sally and a ditty to The Beatles 50 years on. Yet the sketches feel a little dated at times and, often after promising starts, seem to fizzle out before we reach the punchline.

Of course by the very nature of the sketch show format, it could all change next week, and Harry and Paul could return to deliver a show crammed full of raucous material that will have us sliding off of our sofas with mirth. Given their track record, we certainly wouldn't put it past them, and there's enough on offer in tonight's opener to justify tuning in for next week.

The golden boys of Gavin and Stacey, Mathew Horne and James Corden, were rewarded with their own sketch show on BBC Three, which attracted a record audience of 817,000 for the first episode. After that, it was downhill all the way. Directed by Kathy Burke, the show was roundly slated for being amateurish, crude and aggressively unfunny. Viewing figures collapsed, with only 434,000 bothering with the final episode. In one sketch, two teachers give a joint lesson to a class on how to draw penises; in another, James Corden keeps shouting "I'm going to come!" while having sex. Elsewhere, he pulls up his shirt and rolls his stomach in front of a burger bar as a form of consumer complaint. The acting is accomplished enough, but that's as far it goes. Viewers on terrestrial television can now find out what they haven't been missing.

Two stars of Gavin and Stacey, Mathew Horne and James Corden, now have a show of their own. Like so many sketch shows, it is a wildly mixed affair. The best of it is the quality and variety of their acting, which is spectacularly accomplished - these guys are very, very good. One sketch in particular, in which Corden plays a seedy, down-at-heel wastrel who embarrasses an old schoolfriend in front of his family, is a masterpiece of loathsome observation. The downside is that much of the material is crude and horribly unfunny. It is no surprise to discover that the series was directed by Kathy Burke, who was never likely to add a lightness of touch. In one sketch, two teachers give a joint lesson to a class on how to draw penises; in another we meet a gay news reporter; elsewhere, Corden pulls up his shirt and rolls his stomach in front of a burger bar as a form of consumer complaint. Nice.

Are Mathew Horne and James Corden the next Morecambe and Wise? On the strength of this, probably not - and the quicker Corden starts writing the next Gavin & Stacey series, the better.

What differentiates this from other sketch shows is that some parts were shot in front of a studio audience and it was directed by Kathy Burke - a comedy god. But it's the usual hit-and-miss affair of sketches that work (superheroes meeting off-duty, a camp war correspondent and a brilliant Ricky Gervais impersonation) and those that don't.

There's a surprising amount of naked flesh as the lads seem to get their kit off at the drop of a hat. The duo's popularity should help them ride this one out but as their awkward stint presenting the Brits showed, being mates is one thing - creating that effortless on-screen chemistry is a lot, lot harder than Ant and Dec make it look.