Echoing all the positive sentiments in here- absolutely loved my 4 days at Mad Cool! Everyday we started with a bang (Wolf Alice, Nothing But Thieves, Local Natives all really good). And ended just as fantastically with Alt J, Foals and Florence. A lot of bands I thought I'd lost interest in but just the right amount of nostalgia and good new tunes made it an almost perfect festival.
Also struggled getting back on the Wednesday- we were staying at Plaza Castilla and stupidly couldn't find the shuttle bus but every other day was a breeze.
I went to Primavera last month too, and the difference in the crowd was the biggest positive difference- spacious and comfortable but not at the expense of atmosphere. Thoroughly enjoyed!