M+ is not a fun experience.
I’m not top of the top, but I am 2500+ io currently trying to pug and complete 10s with mixed success. I usually get close to title, but never have the group to actually push it so my experience is 100% from pugging/occasional guild keys.
I have not had less fun in a m+ season than now. M+ is abysmally bad. Below I will i List the Positive and negatives I have seen.
Dungeon Design:
PRO: This I am generally happy with. I like the old dungeons coming back. I like that they added mechanics to them. The design of the new dungeons is also really fun.
CON: Necrotic wake… the third boss is a nightmare. They changed it so that the damage output on the creations is INSANE and you have to either save hero, three spears and try to one phase the boss… or, if your DPS isnt up to par, you have to focus the creation down making the boss fight take forever. This needs more tuning. MUCH more tuning. Also, having some of the dot damage from adds, like in COT, do more damage than tyrannical bosses is pretty wild.
Dungeon Timer:
PRO: for most of the dungeons, I think the timer is very good.
CON: The 15 second death timer is ABYSMALLY bad. Why put this in blizzard. what purpose does it serve? This undeniably makes pugging 1000% more toxic. People leave dungeons after a few deaths because the timer is already so tight, that any dungeon with 6-7 deaths is a waste of time. People spend hours waiting to get into keys, or build their own keys up just to this level of natural toxicity hovering in every dungeon. It actually incentives you to not push your own key and just hop into someone else in case it gets ruined. Its the dumbest addition they added.
Dungeon Affixes:
PRO: They got rid of a lot of really bad weekly affixes. At level 12, affixes are gone and it’s just pure damage, allowing key pushers to avoid “push weeks” and “non push weeks”
CON: They added an affix that is 20 times worse. These balls, on a lot of bosses that add area of denial abilities (which is…a lot) are so insanely hard to collect that sometimes its just a wipe. The timing of these balls with boss abilities is just horrendous. Some examples below:
Ara-Kara - All three bosses have movement mechanics. Either webbing on the ground. entire room area denial, or a stun to prevent being pulled in.
COT - First boss has a tiny circle you have to stay in and more around to avoid frontals, debuffs, ground goop ect. Last boss has an aoe web and tons of aoe damage where just one ball goes in you are toast. Third boss has tons of ground goop.
I could list out all of the bosses, but you get the idea.
Rewards:
PRO: Hero track gear
CONS: Weekly vault, many times, does not yield very good results. and in dungeon rewards are just not as fruitful as raid.
Some fixes.
- 
Move the death timer to 12+. Those keys don’t deal with affixes and they are going to be generally always done for IO so one wipe usually kills a key regardless of death count. Don’t punish pugs that are already a chore to find and deal with, and that will most likely never get past 10/11s 
- 
Give us an option to acquire currency from the vault that could be used as RNG bad luck protection. This way, if we have been waiting for a mythic Sac trinket for 6 straight weeks and taking the currency…we could have enough to buy it from a vendor. This would allow people to not feel that their effort farming keys for a week has been wasted. 
- 
Revamp the ball affix to not proc during bosses. 
- 
Be more aggressive in tuning. Clearly it is extreamly bad when a boss requires paladins to clear tentacles (Grim Batol last boss) or a boss that requires significant ST dps classes, 3 spears, hero to one phase otherwise it becomes a wipe… 
Just my two cents.