I completed all 10 acts today. I haven't dived into the end game and I'll probably start a new character for the expac tomorrow. But here is what I think.
For a free game, its outstanding... its hands down the best F2P game in existence. I'm not judging this by the actual game, but just the sheer amount of content that isn't bullshit. If you want to just casually play 10 acts for the story. Its way more bang for your buck or lack of buck. You get everything for free.
If you want to play this game a little bit more seriously, like endgame content or or multiple characters, you're going to have to spend about $15-30 depending on your convenience preference and if there is a sale going on. As both me and Strider pointed out, inventory is a joke. Your on hand character inventory is pretty limited and fills up quickly. The stash seems fine at first, but if you horde flasks and attack/support gems, by act 4 or 5, you're going to be running out of space. The game has normal extra stashes and more detailed stashes that organize your currency, maps, and other specific items. For the short time I've been playing, Stashes have been 50% off twice.
The currency system is utterly bizarre at first, but when you get use to it, its less of a hassle and kind of a non factor. The scrolls of wisdom thing was annoying at first, but then they started dropping more than I needed them too... as it stands now I have 780 in my stash.. I never found myself needing them too often. Other currencies like jeweler's orbs and fuse orbs that are actually useful but frustrating to come by are a bigger issue.
Drops are trash all the way til the end. Its probably the most disappointing aspect of this game. Loot never really feels rewarding outside of trials of ascendancy. Since jewelers and fuse orbs are hard to come by, its hard to get a max socketed item all fused for your gems. By the end of act 10 I never had a fully socketed item outside of my helmet and gloves. I only changes Bows less than 4 times because the one I had used more sockets. By the end I had one less than the max sockets for my bow. All the unique items that drop are pure garbage, and the good ones come from grind.
I appreciate the detail the game has in dialogue, but it definitely isn't a game you can plan to play for just 1 hour. You can spend it all listening to characters talk. When you find a document in a map, you can click on it and walk away so the dialogue continues to play, but interacting with NPCs is annoying because you have to sit there and listen without doing anything if you want to hear the dialogue... sometimes checking your inventory, or fiddling with anything will cancel the conversation.
I plan on playing league when it starts tomorrow because the drops seem way better... but for standard the death penalty is just losing XP for that level. I hear once you get past 80 (max is 120), these penalties are brutal because XP is more scarce and dying can wipe 2-3 hours of progress. Overall it seemed kind lame and super casual, but at the same time, the only thing that really kills you in this game is one shots from bosses and strong enemies. Playing ranger, you cant move and attack at the same time, which is an adjustment. So its a bit easier to die than it should be.
The amount of different attack and support gems is insane. I eventually had to divide my gems into 3 stashes for red, green, and blue. I now have half a full stash of each. This game shines in the fact that there is no class specific items... only melee and ranged specific. I haven't encountered any armor or weapons that said I couldn't use it.
Its worth checking out on PS4. It may not be as refined as a Diablo game, but its a great dungeon crawler to pass the time. I just hope we get a western release for Lost Ark, because that game looks really sexy.