This is not an in depth review but a basic once.
Tom Clancy's Rainbow Six Siege is an absolutely stunning game, not only the graphics but the sounds as well as character movement. There are a few downfalls one being the lack of campaign mode which instead has "situations" mode which allows you to complete certain "training" levels to in my opinion get you ready for online play. This is pretty handy as without this I felt I sucked in most situations online without learning the basics.
Siege is a tactical shooter, When I say tactical just pray you get a good team online who actually work together and not a bunch of douche bag 12 year old's who's prime intentions are to just rush the map and usually fail with you looking like a complete fucking idiot with them. If you manage to get a good team together however you will have a good time, being everyone having headsets on and using certain character perks to dominate the game.
I got this game when it first came out and HAVE experienced connection and loading issues especially the wait time to load into a game, this gets really fucking annoying however be patient i'm sure Ubisoft are going to fix this ;)
Jokes aside I think this is one of the best fps by far when it comes to realism and military tactics and is a must to play on the XBOX ONE! ;)