Unfortunately, this is probably the best yugioh sim ever made. Great accessibility, easy to pick up and fun to mess around in. However, this all comes at the cost of the gacha system - extremely hard to get cards you need consistently and can be hard to build multiple decks you want to use for this reason. The crafting system is excellent but you'll typically find yourself lacking SR and UR points pretty frequently. I've found it's best to plan around building a specific deck you'd like to play with for a good period (espc if you are F2P) so you have some consistency.
That being said, this game is also surprisingly free to play friendly as long as you're not itching to make multiple meta decks. While i can sympathize with new/returning players logging on, running into kashtira/vanquish soul/purrely, etc. getting chained into oblivion and getting frustrated with how much the game has changed, this remains the best way to experience a yugioh sim and i appreciate how it's let people (including myself) reignite their interest in the series.
As improvements, I would like to see the game's card base updated more frequently (as many others have brought up) as we're missing a lot of recent staples, and would like gems to be more frequent, which would fix some of the issues with the gacha system.