Releasing the final game of a trilogy on a new console seems a strange decision, especially since a major feature involves importing your character from previous games. The Wii U does not have such a feature, but instead, you can fill in key decisions and learn the back story using the interactive comic. Although it's no substitute for not playing the previous games, it's a nice refresher course of the story so far. If you haven't played the previous games, then it doesn't make much sense to start here given the story-driven focus of the game. That's not to say the game-play isn't good, but a lot of entertainment is achieved by participating in the massive universe which is full of lore.
In terms of story, Commander Shepard must recruit an opposing force against the Reapers, a parasitic-looking mechanised race which is content on harvesting organic species. The entire galaxy is under threat, but alien races are caught up in their disputes, and the Cerberus corporation is up to no good. Therefore, Shepard must resolve conflicts, rally the troops and try to thwart Cerberus' plans.
The conflicts you do resolve can include some major decisions which have massive consequences. Plots that have been developing such as the Krogan genophage, and the Quarian vs Geth conflict can finally be resolved and the climax to each is rather emotional. Along the way, you meet some new characters as well as familiar faces. It does seem a bit silly that you stumble into your old squad-mates on each mission involving their species; it often gets predictable and ruins the surprise.
The game is impressive with its presentation. Those that doubt that the Wii U is capable of even competing graphically with the Xbox 360/PS3 will be proved wrong. The script, voice acting and general cinematography are wonderful and often feels like you are watching a movie (one that lasts 26 hours or so anyway).
The game is extremely long, but you can cut down a lot of the missions. However, doing so will make you miss out on the better endings. For every mission you complete, your army numbers will increase and so will give you a better chance of survival in your final mission. In practice, you need to fall within a certain thresholds to qualify for each ending. Bizarrely, your total force is multiplied by a figure called Galactic Readiness, which is linked to how many times you have played multiplayer.
You may think that given that the game is now over a year old and on a low selling console that the online community would be sparse. But I had no trouble getting games at the time of writing (20-Dec-13), so it doesn't pose a problem. Multiplayer is rather fun, and you team up to defeat 11 waves of enemies under various objectives (defeat enemies, disable objects, escort a probe, capture the flag etc).
In terms of combat, it's basically the same as before; third-person cover-based shooter with support from special tech/biotic abilities. You can order your two supporting team mates to use these powers and switch weapons for some extra tactical decisions. You can bring up a radial menu to do so which pauses the action, or alternatively tap the icons on the Gamepad which you need to configure yourself. The Gamepad also doubles up as a handy map, which is very useful. It is convenient to stop shooting and hide, glance down to check your map, pop out of cover and shoot at your next target.
There's plenty of guns to find and purchase, each can be upgraded with two weapon modifications. There's plenty of armour too, and you can switch individual parts to create your own armour and even give it custom colours. The heavier your load-out, the longer your cool-down period is, which means you will have to wait longer between using your powers.
The major disappointment for me was how the Citadel sections have been stripped down to be the most boring area in the game. In the original game, the Citadel was huge and there was so much to see. In the sequel, you were limited to areas, but it still had the feeling of being a large and important place; just cut down for usability. In this game, the Citadel feels tiny and lifeless, with not much going on, simply relegated to some stripped-down quests.
Mass Effect is pretty much epic from start to finish. It does start to get a bit tiresome towards the end, and it does seem to come to its conclusion on the weird side. However, there is no doubt it's a great game and a brilliant series, it's just a shame the whole trilogy wasn't brought to the Wii U.