I've found the mayhem missions to be a real mixed bag.
On the one hand the Atlas Park, King's Row, and Skyway missions were a lot of fun, chok full of smashing cars and crates, and fire hydrants and what not. I very much enjoyed the side missions, be it pawn shop, arson, kidnapping, etc...
However, once the swat team appears all fun vanishes. Flashbangs and glue arrows stack up quickly from even a handful of these guys. Whether with Brute or Corruptor, if the swat team got the drop on me I was in for a VERY long fight (minutes). Miss, miss, miss... crawl, crawl, crawl... this is NOT fun.
I think the stacked debuffs need to be examined, whether in duration or in recharge, and reduced to a sane level. Standing around unable to do anything for minutes at a time, either slowly dying or equally slowly winning is not fun. If the swat team is supposed to be so tough, why not drop the debuffs and triple their damage? At least things would be decided quickly one way or the other.
A more practical consideration is, if there's such an abundant and well equipped swat team that can respond en masse on a moment's notice... why on earth are there even heroes?! The whole game of CoH is invalidated by these extremely potent minions. If they were more like Malta (with the sappers) or Longbow (with the 40+ Spec-Ops) and there was one key baddie to neutralize first, that would encourage smart strategy and be managable. Having 4 minions chain debuff you into total ineffectiveness... and then spending 3 minutes beating you down is boring and frustrating. I for one will not waste my time on Mayhem Missions that include Swat teams, if they go live as is.
One other smaller point, why do ALL the cops in the Founder's Falls missions have to be Psi? This seems unbalanced towards /Fire and /Invul, since above level 30 so many of the enemies use attacks other than Smash/Lethal. Couldn't there be a mix of enemies? Just a thought.
Overall I appreciate the destructable environments and the side missions and the wonderful prizes you can find, but the swat team and their silly/potent debuffs sap the fun right out of the missions they appear in.