I actually really like the stage selection this time around. My offline multiplayer play-time is generally a lot of party-style play with friends, so I don't have a problem with non-competitive stages. I actually like many of the hazards, even the Yellow Devil. The hazards damaging you is fine in my book; my only problem is when the hazards become so powerful that they are getting more kills than the fighters themselves. The 3 stages I dislike most are:
75m: There's no place to actually fight here. I feel like 95% of deaths are caused by the stage destroying you as you desperately clamber around looking for solid ground. The only passable platforms for fighting have those stupid fireballs on them, so fights here basically end up with you getting ping-ponged around until you miss a jump and fall to your death.
Flat Zone X: Again, the hazards on this stage are completely deadly. And to make matters worse, the blast zones are miniscule. They picked the absolutely worst Flat Zone forms to compile for this. Lion Tamer is stupid. The fights I've had here mostly amount to running like mad from all the stage hazards which move about randomly and deal death at absurdly low percentages.
Yoshi's Island: There actually aren't any real hazards here, but the spinning blocks ruin everything. 8-player smash is ridiculously chaotic here (it's one of the worst options for 8-P), so you'll probably die at least once or twice just because you fell through the blocks without even knowing where you are. It's deadly and not at all fun, since the only real place you can go to avoid the blocks is a slope where you are easily thrown or bumped off screen.
As for other smaller problems I have, I don't like how hard it is to tell what is a platform on Orbital Gate Assault. And despite how they clearly tried to make the transitions safe, I've still been dropped through the tiny cracks between planes too many times for my liking. Yoshi's Woolly World is interesting, but I feel like more platforms should have had grabbable ledges. And lastly, Palutena's Temple and the GCO are too big. Even on my >40 inch TV I struggle to pick out my character. Plus, it's impossible to die on Palutena's Temple. I generally favor Time matches in 8-P Smash to prevent running/camping, but most 2-3 minute Time matches in the temple only result in maaaaaybe 1 KO per person. Hyrule Temple is the only stage that I feel perfectly fits 8-P Smash.
EDIT: Also, I like Pac-Land. The hydrants are annoying and very dangerous, but the graphics are hysterical, the music is great, and I've had a lot of fun fights here.