I've only played a few games on the new client so far, but there's one huge issue that I think needs to be addressed immediately. When "something" happens, the interface HAS to show it. When I say "something", I mean anything Dominion related -- playing cards, revealing cards, moving a card from one location to another, etc.
I know many serious Dominion players liked to play with animations off on the old system, and that's probably the reason the new client works the way it does. In the new system it's inarguably harder to follow what's happening. This is killer for new players. If an experienced player has trouble following what's happening, a new player will be completely lost (and will probably not continue playing).
As the new system currently works, there's a ton of information that is ONLY visible if you check the log. The log needs to be a supplemental source of information that simply lists all the things that were shown through the interface. In other words, it needs to be possible to play without consulting the log at all.
Here are a couple examples of the problems related to specific cards that I've seen in just the few games I've played.
The revealed card isn't actually revealed. I don't have any idea what it was (until I check the log). Or say you hit a big chain of Heralds -- you don't see any of it. All you see is that suddenly the Herald you played has a "3" over it, and some numbers in your hand changed.
Same issue with the revealed card. "Wait, did another copper just magically appear in my hand, or is there still a card on top of my deck I should know about?"
Instead of revealing an actual card, there's only text saying "a copper" and asking who should gain it. There should be a big picture of the card on the screen while the players makes their choice.
I self-trash a Raze, and "nothing" happens. Checking the log, I can see that 2 coppers were revealed, so one of them is now in my hand. I'm all for removing the stupid decision of which copper I want, but at least flash them up on the screen so I can see what's happening.
Once again, I play it and then my hand has magically changed. Did I draw the first two cards of my deck, or did I cycle through the whole thing? Half my Hunting Parties could have been only drawing a single card, and I wouldn't have had any idea it was happening.
I think this issue is hugely important. If it's not addressed, I think this will single-handedly kill new player adoption of Dominion Online. Clicking a card and having a multi-step process resolve instantly is not only confusing, but it's just not very fun.
I have a few other small pieces of feedback/suggestions, but I'll report them later. I want to keep this thread focused on this one issue because I really do feel it's vital to fix it immediately.