Unlike its predecessor, Mission X could be overwhelming at first. It's the mission in which you should infiltrate some huge and posh casino to make some sabotaging. Also you re not alone, and your work is to assist your "colleagues" from Circle of Stone and Shadow. Your actions help them to reach theirs, and if you fail your job, the game is over. The scope of both building and your task is tremendous, and not many missions, original or fanmade, could equal this mission. Perhaps, the closest thing from OMs is First City Bank and Trust, also amazing mission of enormous proportions and sometimes tough puzzles to solve. Although, Mission X kind of improves and complicates comparing to Bank mission. Also, in terms of general "look" and "feel", the mission is somewhat close to later Dishonored games than to more gritty "usual" Thief experience.

As I can see, it sometimes is considered as more technological achievement (in which "technological" somehow is countered to "gameplay" and "fun") rather than playable fan-mission. Another point is that it's too hard and overwhelming. And the last is that it is full of bugs. Maybe the last one is easier to counter since now it is bug-free (more or less). As for question of difficulty, the authors deliberately decided to rump up the difficulty by removing the tips from your mates on higher difficulties. Perhaps the best way to play it on first run would be lowest difficulty level. As for the "tech vs fun" claim, I would say that it is the most subjective thing from all: firstly, for me new gadgets (like mask) in MX don't change the game much, serving mostly as a (optional) pointer or additional tip of what to do next (like mask again). And then, let me be clear that Mission X first and foremost is quite challenging sandbox thiefy mission at its finest: it has lots of additional ways to traverse to higher and lower floors of casino. In that regard it paradoxically succeeds more than as collections of tech gizmos which not change gameplay that much.

It is not to say that there are no nitpicks here. Rubber's quests are quite the chore (even though being optional). Also the mission actually forces you to perform your main task immediately after arriving (like in the beginning of Midnight in Murkbell). Sometimes it is not always clear if your actions actually helped your squad-mates (the mission doesn't immediately tell you if you perform your action correctly). Combined with aforementioned lack of tips on higher difficulties, it could pose some annoying problem. So I recommend to save often and to consult walkthrough if needed. But perhaps despite the problems, the mission is more than sum of its parts, even if it could be frustrating at times.