Deciding how to start this post was hard. But what I arrived at was a rather clever piece of meta in my opinion.
Bla bla bla, Mass Effect 3, bla, bla bla, RPG, bla, lets just jump right in and sweep over all the little remaining systems I want to talk about for now before I start scoping out another game to discuss.
First off, let's hit the weapon upgrades. I actually like the way Mass Effect 3 handles weapon upgrades. You collect a variety of weapon upgrades which you can assign to upgrade slots on each weapon. These upgrades improve ammo capacity, damage, etc, and can add special abilities to a weapon. Some upgrades are only compatible with certain weapon types, and each upgrade is useful and meaningful in a different way. There are few enough upgrades that you aren't constantly just switching out for the next biggest thing. It's not a bunch of busywork, put simply. This mixes with the character creation and upgrade system to add very large incentive to play through multiple times.
Said character system is kind of interesting. My experience was coloured by the fact that I played through all three games as an Infiltrator. See, the first two games seemed to handle Infiltrators well. The maps were set up so that your cloak could give you a tactical advantage trade-off, but didn't brake the game. However, Mass Effect 3 will be full of game-braker moments and humorous cutscene inconsistencies for an Infiltrator who likes to cloak. Still, the game does a good job of providing you with a lot of interesting decisions about how you will roll and upgrade your character with an ultimately palatable result.
So now you all know that I can take a game that ultimately disappointed me and point out some good things about it. But enough with that, let us(meaning me) talk frippery-ness about things like the pathetic space and planet exploration/resource harvesting.
In the first Mass Effect game, you could go down to a crunk ton of planets and speed around in a vehicle to do exploring. Yes, steering the vehicle was about as smooth and accurate as steering a jack hammer through tomato paste, but at least it made the galaxy feel big and made exploring interesting. The game caught flack for said vehicle controls, so they threw the vehicle sections out the airlock in Mass Effect 2 in favour of a minigame where you could explore solar systems to scan and mine planets for their natural resources and use them to build upgrades. It did make the universe feel a little more constrained, but at least it was an alternative to the last game's tacky vehicle sections. In Mass Effect 3, it all goes away. You just emit "scanning pulses" from your ship that tell you if you're near a planet or wreckage with resources to collect. You can then scan the planet or orbit the rubble to collect your resources, but it's never rewarding enough to waste your time on it. To top it off, this useless exercise risks getting caught by the reapers in systems they control, completely removing any reason for a logical player ever to use the resource gathering or exploring features. In Mass Effect 2, you pretty much had to mine planets and explore if you wanted any significant part of your crew or ship to leave the game alive, and in Mass Effect 1, the exploration was central to the game and did a good job adding enjoyable and plausible depth to the universe, but in Mass Effect 3, it just seems like filler around the boring shooting which is there just because it was in the previous games.
I know I don't review games any more, but I want to say this: All in all, Mass Effect 3 is a passable game, but I really can't label it as great. It's not just that I liked its predecessors better, and it's not just that the ending screwed up. While the story ties up a lot of important loose ends, the gameplay is really pretty frippery, and there is still a lot of bad writing to be found. So it's not really bad per se, but it's definitely not really good either. But whatever you do, don't play the ending. It will ruin the series for you. Just stop after the mission "Priority: Cerberus"