I had a go on one of those things once and it was horrible. Admittedly the sail was tatty, there was no tiller extension and the toe-strap broken, which considerably coloured my opinion. The wind blew up and I found I couldn't tack into the waves because without a toe-strap I couldn't get it going fast enough. Ended up bearing away, gybing, capsizing, and bobbing around out of sight of shore (due to torrential rain). Not the nicest of moments.