I was so excited when i saw the detailed presentation by Ian Hazzikosta about Delves.
It was a dream possibly coming true. A solo encounter, mostly, where with some effort you can get also gear that groups must get from high raid and mythic dungeons.
The reality is harsh
At delve 8 with a gear at 590 (600 suggested for delve 8) it was challengefull and time consuming but i loved it, you must take your class and spec and talents to the max, make that brain of yours think outside the box , abuse mr Brann a little as dps/tank and play your best and fast. At least for enhancement shaman.
I got frustrated in my 3rd Delve 8, died 2-3 times from mistakes and died more than 5 times in the end 
so i decided to check the groups. I joined as restoration shaman and a classic group of tank , 3dps and healer (me) just passed through like a stroll 2 delves in 20ish minutes which gave 603 items as bountiful if you had a key.
What a disappointment…
As solo i had to face a last boss at 63 million hp , without tanks with me or healers.
As group the last bosses were at 123 million hp, with tank, healer, dps and many utilities…
MY conclusion is
Delves were not ready to get out in the retail, their promise and reality is 2 distant things which really destroy the reason they were created. And that is Solo encounters or play with friends (and we all assumed equal difficulty.)
Solo is tough , group is faceroll. Tuning sometimes is so weird and ofc no way some specs or classes can perform as easy as others (thats maybe ok)
You made me feel i was cheating because i groupped and did 3 delves tier 8 in 10-12 mins each, where i spent 3 and 4 and 5 times more to strategise and play at my best in solo delve 8s…
Delves have become/fallen due to Blizzard’s incomplete development(i guess), as a quick stepstone for fast gear 603 with groups that dont even interrupt casts or monster deadly skills (in contrast with a solo delve 8 where you must time everything and in correct order)…
Very disappointing retail result…they need rework fast and i feel ugly for going to groups 3 times. I want the value of the solo effort to have a meaning. I dont want to see effort of this magnitude being trash and garbage of time because a group can just stroll in hitting everything and cleaning it in 10mins…
Ofc the rest might not care, might see it as a quick loot chance as groups, but that is nto what the delves were made right? Delves were a new promise and they were not materialized properly.
Mr Ian i want you to deal with it and make it fun…not faceroll groupped…worse case make it 1 to 2 or 3 man with extra monsters , make those extra people work for it in tier 8 and up… or make it 2 man max 