Absolutely nothing wrong with acrylics, and many modellers today know nothing else. For my part, having used enamels for so long, and long, long before acrylics were even in prototype form, I guess it's more a case of 'the devil you know'. Having said that, and I know people might disagree, I find that acrylics do not have the versatility of enamels, when it comes to working with a paint brush (as opposed to an airbrush), and when subtle blending techniques are required. I'll admit, part of this is due to my not really trying to experiment to see if it is possible to achieve similar brushed effects, but, although some effects probably are possible, I doubt that all techniques (employed with enamels) and results will be possible, due mainly to the make up of the acrylic pigments and carriers.
I do agree that acrylics used in an airbrush are very good indeed, although they often require a primer, and are not quite as hard wearing in the early stages of handling. As for easier clean-up with acrylics, in general this is true. But, the nozzle will clog easier, and a 'quick' clean will lead to further build-up of the medium, which tends to 'plastisize' when dried on the needle, jet and nozzle.
However, with the change (for the worse) in Humbrol paints, and the possible future restriction, or outright banning of enamels, I think i will have to change to acrylic paints, more than likely Vallejo.