Induction is claimed to be more efficient, at least by 20 percent. You directly heat the bottom of the pan without having to heat the hob surface, or losing heat to the air before it's even had a chance to heat the pan. The magnetic field heats the base of the pan directly, and so it works much more quickly and efficiently. You can get a frying pan smoking hot in 30 seconds or get a pan of water boiling like you're using an electric kettle. Certainly our bills have gone down since we switched from gas cooking to electric.
Induction hobs are much easier to clean and keep looking good because they don't generate heat, so they don't bake spills onto the glass. They get hot from having a hot pan sitting on the glass, but they don't carbonize spills like a gas ring or halogen does. Induction cookware is all over the place now, so it's not expensive, just look for the induction compatible label.
You also get the benefits of things like automatically switching off when detecting no pans on the hob, alarms, timed switching off of individual rings, locks to stop kids or cats turning the hob on, etc.
If you had solar panels on your house, it would also make a lot more sense to go induction (as my in-laws have just done), because you're better off cooking with free electricity than paying to cook with gas.
I've used gas, halogen and induction, and induction is my favourite. I've converted a few friends and family to them as well, because they've seen mine in action. Maybe the very purist chef might not want to go away from gas, but for most people there are benefits. I certainly wanted to stick with gas for our new kitchen having lived with a halogen for a few years in my younger days, but my wife insisted on induction, and it's completely the right decision for us, and probably most other people.
What size mcb would be needed in my consumer unit for one?
IIRC, I've got 40 amps in mine just for the hob. You may need new wiring, because they can suck a lot of power. They also need one of those big 40 amp isolation switches, like you get for an electric shower. You don't fuse them as a fuse would melt under load, they go direct to the consumer unit on their own circuit, and you use the MCB as a breaker. The back of the unit the hob sits in also should have a cutout for ventilation, as there is a fan in the bottom of the unit to cool the electrics.
