Some constructive feedback from someone who just tried playing online for this patch (please treat as constructive input, I'd like to see MP work well, but I don't feel that it's there yet).
First, I always felt that the design of d2 was a bit rubbish with having to repeat the same content 3 times in norm, nm & hell.
At least in old d2 you got a reasonable feel for how well the class was going to play whereas in median it's a walk in the park through the first two levels and most of hell. Only ubers are a real challenge. And I'm not saying that the solution is to make them harder, as I said that was always annoying in d2 anyway - and in d2 you could use cows to powerlevel.
Another factor here is that previous median versions changed d2 content (quests etc) but now the old d2 content has been set back into the game it's like levelling of 20 years ago, why would I want to do the same thing over and over for 20 years? And these 'quests' were boring then, they don't get better with age - what is the point of the A1 merc quest in nm and hell? Or the countess? Why doesn't Anya give us an amulet that is guaranteed to be good instead of just another random rare?
I've found this patch frustrating. I decided to try playing online instead of SP. What a mistake that was. The devs suddenly decided to nerf a couple of the new builds and took them from powerful to "I wish I hadn't chosen this class/build" in one step.
Also, I found that another old problem with d2 is still true here. Public games are useless. Example: I try to join a game called "Act1 nm" and find that they are in act 5 (they didn't bother to make another game with an appropriate name after killing Andariel). So I join another game and play through act 1 on my own while they are in act 2, so when I get to act 2 I have to join another game since everything is dead in this game's A2. So I join a game that says "A1 A1" and this time they are in A1 and they start shouting at me for doing their content in A2 (missing the point that they shouldn't be doing A2 content in a game called "A1 A1".
And on it goes. The only people who seem to be getting any fun from MP seemed to be people who were playing and making games together as friends, probably in real life. All in all, I never played with other people in any meaningful or positive way in the TSW servers. In the end I gave up and made passworded games.
Since I never got as far as having anything useful to trade, I never used that feature. With the public gaming being useless (and no pvp) I found the whole multiplayer experience worse than useless - it was actually worse than playing SP in every way, especially if you add in issues such as games dying or locking up, servers going down etc.
None of these problems exist in SP and I can powerlevel a new character by copying an old one, which means I only have to level each class once. The only downside of SP is that the items don't get changed to new versions of the same thing, so some can be over- or under-powered and I may not be aware of it (such as new set items) unless I know almost every word in the docs inside out. But then it's probably a good way to play SP if we throw away all our items except what we're wearing and start our items from scratch each season - at least that way it is like a fresh start, just with a newly-levelled character.
Yes, there are lots of ways to cheat in SP, so it needs some self-discipline since in the end you're only cheating yourself. And it depends how you define cheating. If an uber is seriously boring and time consuming (to my mind, which is the only one that counts in my games) then I can do it once and dupe it into other characters.
Just my views based on my experiences so far in MP, please don't shoot the messenger
Suggestion: In each account, after hell mode is unlocked by one character, make it possible to make a level 104 character and start in hell.