I'm in the same boat. Mafia 3 is a cross between a trainwreck and a fun interactive story. Some elements were done well, but it seems to suffer along with most of its modern counterparts in that performance is either great for you, or total garbage. Sadly H13 haven't fixed that issue, so it's still glaring.
The gameplay itself, beyond the repetitive parts, isn't too bad. The cross-map missions irritated me more than Andromeda did recently (honestly in the case of the latter if I could just straight planet-hop I wouldn't care as much); having to drive slowly across the map, or even rip-tearing fast across in one of the nicer cars, is painful and really makes the game unpleasant.
But I did enjoy the story, which is part of why I wanted it. Sure, it had issues, but all in all it was pretty well put together, and did what they said it would do in terms of pointing to things that are horrifying. My biggest disappointment was the community around Mafia 3: racism was off the charts, snide remarks pretending not to be were everywhere, and the level of denial was incredible. Now, being Australian, I haven't had to live in the shadow of that particular past (we have our own shameful racist past), but I fail to see how screaming how it isn't so and then posting the same sort of ignorant crap in another thread doesn't highlight the issue. I wish the game could raise more awareness of that part alone, as I'm tired of people being jerks over things that honestly don't require jerky behaviour.
I could go on about this issue ... anyway, tl;dr: honestly, Mafia 3 did a great job, showed an alternative Mafia type, and even though it was repetitive it was quite fun and worth it at full price (as I preordered and stuck it out). I need to play the DLC that's just come (as I did preorder the deluxe), but I doubt I'll be disappointed given who the main character in it is
Edit: To clarify, the reason I'm excited to play along side Donovan is he's a wisearse CIA operative. The only part that's relevant here is that he's a wisearse. Being a CIA operative doesn't hurt either, but I mean, come on, who didn't play Mass Effect (1/2/3/A) and just pick wisearse choices, at least in one playthrough?
Clarity Edit: For some reason my brain decided "play as" instead of "play along side". Running commentary is all I was really keen on, and it's what I got. As a general first tip, when you start the first mission (the pick up of Donovan), fiddle with the radio station
Edit #2: Having played a bit now, I'm enjoying it. Donovan is the wisearse I thought he'd be, and the story is grim/evil/CIA-ish. Working out so far. By way of a non-spoiler, more of a "yeah, you do":
Still disappointed in the community, as it seems every patch, even the minor ones, seems to revisit the racism =\
I do wish developers were more honest with "we have some ideas, and some funding left for things to do", rather than leaving a game feeling incomplete, but working on it in the background. Mafia III is a really solid example of that, because despite there being known about DLC at launch, the cost of the Deluxe copy being basically a full fledged game (and the DLC fleshing out the rather light base content well), it feels like they were waiting for direction from us.
On the DLC note, this is actually, from what I've seen, quite well done, quite well thought through, and seems to fit with the story of the game (from what I remember). It also really highlights the roles (Lincoln gets it done, Donovan is a hardarse wisearse who's seen some stuff). To me, being from a completely removed culture, I don't care who is what, just as long as the characters and story hold, and they do. If you like the base Mafia III, I get the feeling you'll like this. Having done the first mission (and now the second it appears), yes, you do have senate inquiry clips to enjoy as part of it. I'm sure, like with the base game, they'll end up on YouTube and the like, but nonetheless, it's worth mentioning the neat little tie-in content is there.