Greetings Imperial Citizen,

I shall tell you some imperial Truth about Inquisitor Martyr (and it's Expansion Prophecy)

First of all citizen, you are looking at a big and long Game, with tons of content, worthy of the Emperor's vast grace.
The SP Campaign alone is so big, that you easily will be between Level 60 and 70, if you want to serve the Imperium by doing all Sidequests.

The Graphics are nothing World shaking. It fits the WH40k Lore, its dark and gritty. A little bit low res on some places but we are not on a Paradise World / Garden World citizen. This is War. You are constantly moving and purging. No time to pay attention to Details.

The Sound is fantastic citizen. The Sound of firing a Bolter or heavy Bolter against the Enemies of Mankind is deafening and truly a perfect representation of the Emperor's Wrath. The Death screams of the Xenos and Heretics dying left and right is purging done right. The Ambient Sounds also helps with the Immersion. The heavy steps of your Inquisitor gives really some weight to his movements. Music also fits but you are more exciting hearing the Bass Sound of a Bolter Round, transforming Xenos into Pinata.

There are a lot of Weapons for each Class. My first Playthrough was with a Ranged Inquisitor and his trusty Bolter Towers, which are great to get enemy Aggro. The variety of weapons is remarkable.
Las Pistols, Lasguns, Melter, Multimelter, Plasma Pistol, Plasma Rifles, Plasma Cannons, Grav Guns, Grav Cannons, Bolt Pistols, Bolters, Heavy Bolters, Grenade Launchers, Flamer, Heavy Flamer, various Types of Grenades, etc... + Melee Weapons like Thunderhammers, Chainswords, Power Axes and more because sometimes, you want to get close and Personal to purge the Heresy from the Face of the Galaxy.
Also you have defensive Items like Void Shields and such. And that was just for one Class.
The other Classes get other Weapons and Drops.

You can Purge Heretics and Xenos the Way you like citizen. If you want to be a litte heretical yourself, you can go with a Psyker Inquisitor. You will be able to cast lightning and more magic stuff. Usually you would be sentenced to Death by a 5 day Phosphex Bath for being an unsanctioned Psyker, but as long as you are doing your service for the Imperium, it will be postponed until it's over.
The other Class is the Assassin Inquisitor, but to me it looks like they are coming from the Vindicare Temple. This is when you want to one hit kill Xenos.
And we have the Mechanicus. It's a Summoner Class. You use Bots, Drones and Combat Mechs. A small Army doing the dirty work, while you stay behind collecting the drop. Your Bots do a better Job than those useless Guardsmen.

The Gameplay is pretty much like Diablo and any other Hack n Slash...or so it seems for the untrained eye citizen. This game requires Tactic and knowing your Surroundings. You will use cover and run from cover to cover, while going Bolters blazing and using your active skills. Almost all Cover can be destroyed, with sustained fire (depending on the Material and your Weapon). The Xenos and Heretics understand that as well and will use it against you. So be cautious or you will witness a second Istvaan 3 drop site Massacre, if you just stand in the open.

The content is as I said: Big. And don't think it's over after the SP Campaign. Oh no citizen. The work and Service for the Imperium extends far beyond than just that. Void Missions, Sector Bar filling Missions, Astropath Missions, DLCs, Warzone, Ordo Missions, cleansing operations, targeting beacon Missions, Tarrot Quests, Arena with infinite Waves (Survival Mode) and PvP. Also more and more Sectors of the Galaxy will be gradually accessible over time (depending on the Devs).

Not all is fine and dandy tho.
Levels are repetitive and have not a lot of Variety.
Missions are more or less the same.
Much of the additional content is basically a Gear check or Grind heavy.
The Story falls flat.

But you are not here for the option to sweet talk to the Enemies of Mankind, you are not here to get your best ancient Relic Items presented to you on a silver plate, you are not here for the plotting, you are here for the PURGING.

the Emperor Protects.