Everyone seems to says Brutal HotS single player is about the equivalent to Normal/Hard WoL, so I'm not surprised to read similar comments here. I'm more interested in how the competitive multiplayer scene is in HotS, and from watching bits of MLG Dallas over the weekend I'm definitely of the opinion that HotS is a MAJOR improvement over WoL.
Games are much more dynamic, faster-paced. It's so multipronged that the observer & casters actually couldn't keep up (they'll get better over time now they know what the metagame will be like). There were some stunning games esp. Flash vs Innovation and Flash vs Life. So much better than the last year of Wings. The medivac afterburner ability probably needs a slight nerf, but it makes for some great viewing.
TvZ in particular is ridiculously aggressive now, in a great way. Both sides have to continually attack to prevent the other snowballing them. It really plays to the advantage of the players with better APM/multitasking, which is how it should be. Protoss need something (photon cannon, oracle or mothership core buff, maybe?) to handle midgame Terran & Zerg. MC managed to win matches only through being super aggressive in early/mid. Something's needed to let Protoss stay in the midgame long enough to permit them to work towards a skytoss endgame composition IMO.
Anyway, I like the viewer experience in HotS so far.