Tread pattern looks identical to the A2, so I'm guessing it's just a compound upgrade. Personally I'm not keep as I find them amazing in the dry but dreadful in the wet, and I'd rather have something that coped with both versions of the British weather, but some people do love them so if you liked the A2 you'll probably like the A3.
BUT
When MPS4 are just £57 more for a significantly better tyre in all conditions and one that will last longer, I reckon you'd be mad to buy anything else if you're at that budget. My prices also from Blackcircles, you may even find them cheaper elsewhere but that's the only place I looked 'cos I'm lazy