I've been to Sketch a few times and enjoyed the food and drinks each time.
They cater very well for vegetarians and meat and seafood eaters alike. So far, all of the dishes I've either tasted or seen have been prepared very well and fuse some interesting flavours (which is important to me).
I think it is also important to ensure you have some pre-dinner cocktails or champagne in order to appreciate to complete Sketch experience.
The venue is run very well and the service is generally of a high standard - for London that is not easy to find.
The interior design is quite eclectic and busy but overall it suggests quality, class, and elegance. A visit to the bathroom (pods) is quite interesting and tranquil.
Overall, a must visit for special occasions, entertaining clients, or for those where money is not an issue.