OK, here is my oppinion of the Volus (so far). As some people might know, I was very vocal in not liking the idea before the DLC was released. And I am still split, so I will accordingly split this post into a lore standpoint and a gameplay standpoint.
Lore:
My oppinion has not changed a bit. Looking at the inclusion if the Volus from this perspective, it makes no sense whatsoever and completely takes a dump on lore. I know about the whole "but the supply auxiliary troops to the Turians" stuff, but still. First of all, auxiliary troops are not frontline groundforces, unless you are talking about the roman empire, so there could be made a point here.
But just looking at this with logic, makes it absolutely ridiculous. The Volus, who have been established through the course of three games as a race, that are not fit to fight a war, the way the multiplayer presents it. That's why they are a Turian protectorate. That's why they are not a council race, despite being the third race to come to the citadel, even before the Turians. Outside of the "comfort" of Irune, they are restricted to wearing pressure suits, that greatly inhibit their mobility. Yes, they do have some kind of military, but those are not groundforces, but airsupport (their Dreadnought and their bombing fleet). They might be able to fight a groundwar on Irune, where they can live/fight without their pressure suits, and are therefore not restricted by it. But the battles in the multiplayer are not restricted to Irune. In fact, right now there is not a single map set on Irune.
And yet now Volus characters are running about the battlefields with the same speed as any other character. they can even do rolls and by that have more mobility than the two old Turian kits. Yeah, that makes a lot of sense. Not to mention the fact, that the second their pressure suits get ruptured, they would turn into a gooey mess in an instant. And they can even carry the biggest guns, that kick like a mule. The moment they fire a Widow, Claymore, Typhoon etc they should fly across the map like a pinball from the kickback. But no, none of this happens. And unlike some people speculated in order to make the idea of Volus work with the lore, they are not wearing big battlesuits.So from this perspective, I still hate the idea and think it was a terrible move.
Gameplay:
If you look at what BioWare did with the implementation of the Volus into the gameplay, they did a great job. They finally implemented true support characters, that might not be able to dish out as much damage, but shine in support roles. I have only unlocked the Engineer so far, but his debuff from the prox mine, combined with the debuff and scaneffect of his Recon mine and the awesome Shield boost power, they can turn into a real asset for any team, when in the hands of a skilled player (read not me

). The gameplay actually can greatly benefit from having one or two Volus in the team. I had a game, where I was playing a Typhoon Destroyer. I had a Volus guy sticking to me the whole time and spamming prox mine and Shield boost. that way I could basically stand in the open, not having to worry about my shields, and shred everything into pieces. I could play my role as a walking gun turret in a perfect way, because of the Volus keeping my shields up.
I like the fact, that they kept them that small and did not put them into mechsuits that make them as big as every other character, it provides an interesting twist. And there is just something funny and cute about those little buggers running and rolling about the battlefield.
When playing a Volus myself, I always try to choose one other teammember who to stick to, usually a guy that gets exposed to a lot of enemy heat, like a bulky Krogan or someone, who uses their shields as a weapon (Slayer !!). And when playing an non Volus character but with a Volus in the team, I always feel the urge to especially look out for the well being of my little shieldgenerating friends.
So I think, from a gameplay perspective, it was a good thing, because it feels like it does enhance teamplay and there are finally real support classes.
Conclusion:
If you can overlook the complete disregard of the lore, I think they are a good addition, because of the enhanced gameplay. But there is still the thing, that we get 4 new Volus kits and afaik no new Salarians. So we will have twice the amount of Volus as Salarians. That is a little disappointing. and the question remains, whether those gameplaymechanics couldn't have been implemented without punching the lore in the face ? I could have seen Salarians acting as support characters just as well. I like the gameplay they bring, but still don't like the idea, that it had to be Volus
tl;dr
Lore gets falconpunched by the Volus, but their gameplay rocks. If you don't care about lore, they are great, if you do, they are kind of iriitating. Personally would have preferred more Salarians instead, possibly fullfilling the same roles.