To preface this, I came out of this film with some mixed feelings, although overall I enjoyed it. I haven't read the other reviews here, so I might be repeating stuff others have said.
I'll not be saying too much about the plot/story since that's not an area I'm very well versed in. Generally, I'm not too big a fan of brickfilms that dig into serious, mature subject matter, but you made it work for Roses. It was a little difficult to keep track of who was who across the time spread, but the issue probably lies in me not remembering LEGO faces too well.
Roses is the result of a long labor of love, and it shows. It has a distinctly "filmic" feel to it, almost in a film noir sense. This is immediately obvious from the black-and-white look, but it goes beyond that. A lot of care and attention was put in the framing and lighting of the shots, and it makes for a great viewing. I loved the "silhouette scenes" in the 1914 parts. Later in the film, the dramatic lighting really worked for me. Some of the car shots reminded me a lot of the "rear projection" technique often seen in older films. It serves almost as a love letter to films of the period, and the influence they have had on this film is obvious.
Another aspect that I think was really good was the audio. The music in particular was well chosen, it felt very period-appropriate. It really helped contribute to and elevate that filmic feel. Similarly, the voice acting was overall quite good, nothing too stand-out but decent at the least.
So, about those "mixed feelings"... they mainly come from some of the technical aspects. I want to say first that with a film like this, you're shooting for the stars, so to speak. With an ambitious project like this you're setting high standards, and while they have been met in a lot of aspects, I do feel that unfortunately it was lacking in some others.
The quality of the recording could be distractingly bad at times. Some of the lines sounded like they were recorded in a bathroom environment, with a lot of reverb. The sound design in general was pretty good, but overall it did suffer from this.
My main gripe, however, is with the animation. I took the liberty of downloading the film off YouTube because I was interested too see what framerate it was shot at - I think it was 24FPS? (The YouTube rip was 30FPS but I think I saw some frame doubling in there... anyways.) To put it bluntly, I think the high framerate was ultimately not a great choice, especially since you didn't shoot on doubles. The problem with shooting at 24FPS is that you will need to animate in very small increments, which makes it very difficult to achieve smooth animation.
Unfortunately, there are parts in the film where it didn't quite work. The second shot overall of the film (at 0:58) where the guy holding the gun takes a few steps forward into the frame, is very jittery and it really took me out of the film. Another sequence (at 11:05) has the main character walk through a hallway towards a door, and suffers from similar jittering. These are the most egregious examples that really stood out to me - especially the second shot, which occured early in the film where you can't really "afford" to break the illusion like that with a technically flawed shot.
Some of the editing choices also looked a little off. The 1956 sequence had some shots where the aspect ratio felt "off". They looked stretched or squished. Compare a shot from 14:00 to one at 12:20, for example, and I think you'll see what I mean. Not sure if this was a conscious stylistic decision (I'm inclined to think it wasn't), but it didn't do the film any good in my opinion.
I wasn't going to delve into the plot too deeply (because overall I think it was great), but I'm a little saddened that a large part of the main character's life, 37 years of him working his way up the ranks in the mafia, was told through a couple of titles. I feel like even a little montage to go together with those titles would have gone a long way. It would also have helped establish the complicated friendship/partnership Roses has with Franco, which in turn would make the "betrayal" and ending a little more impactful.
Also, let me get even more nitpicky for a second here lol. Some of the titles were colored in red, which isn't a bad decision per se, but it felt a little disjointed being in an otherwise completely black-and-white film. It may have worked better if there were some select red-colored elements in the shots (like a red cup, or taillights or some blood or something like that), but with the absence of that it just looked off.
I don't mean to take a dump on your film, and I hope it doesn't come across that way. Overall I really enjoyed it and it was an engaging story, and most of it was done very well. But with the level of quality you strove for, the aspects which didn't achieve that level stood out like a sore thumb instead.
So yeah, that's all the thoughts I have about the film.