Story 9/10
The first four novels of Baccano! are okay - not great, but still far from terrible. Their biggest issue is that they simply bombard you with too much information and too many characters (a good percent of them never actually physically appear - but you'll need to know them anyway). It's a bit much to take in and might make reading the series feel tedious. Then “The Children of Bottle” happens.
“Bottle” is unlike any of the novels before it, starting with an abrupt jump from New York in 1932 to Northern Europe in 2001. It also has a significantly smaller cast and only two characters from the first four novels have any significance in it.
Despite all this, or maybe because of it, it's the novel that really won me over. The central mystery of the novel is fun to unravel and has a profound impact on the rest of the series (though you won't realize how much until many novels later) but the greatest part for me is the introduction of Elmer C. Albatross, a character that always looks on the bright side of life to a terrifying extreme. His scheming is a delight to read about and he plays off the rest of the cast brilliantly.
From “Bottle” onwards, the series really begins to pick up the pace, though the 1930's arcs always tend to feel a bit too long. The interim novels provide a much needed breather (I'd even recommend reading the story somewhat out of publishing order; going from The Slash to Alice in Jails is kind of too much) and even end up stealing the show to some extent.
The 1700's novels in particular are a really enjoyable read for me because of how unlike they are from the rest of the series. They have a much smaller character focus as they are almost completely centered around Huey. Their setting, a small town near Naples during the War of the Spanish Succession, gives them an entirely different atmosphere from the novels set nearer to modern times. And there's this undercurrent of dread running throughout them as you meet characters whose ultimate fates you already know.
The 2002 novels, on the other hand, are powerhouses. The already large cast only further expands and the series comes to what is both a climax and a turning point thanks to the order the books are published (one thing you'll get used to is having storylines spoiled ahead of time that still manage to be shocking when they play out).
As all these different arcs go on they become more and more tangled together which only increases my enjoyment of the series. No scene ends up feeling wasteful in the long run and it's the kind of series that benefits from multiple readings.
Art 10/10 (but not really crucial to the series)
Enami does a good job of matching his illustrations to the character descriptions which makes it easy to visualize them all. And there are some really heartwarming scenes that become more so because of the illustrations (Czes and Maiza's first meeting!). In my experience, that's pretty rare in light novels as illustrations are usually treated like a bonus instead of an enhancement. But since this is a novel, the illustrations shouldn't really be a deciding factor in your opinion of the series.
Characters 10/10
Now, the best part of the series is the characters. Despite the ridiculously huge cast it's not difficult to remember everyone. They all have very unique personalities and their sheer variety guarantees you'll find at least some of them to your taste. In my case, the characters I ended up falling for are the 1711 immortals, especially Elmer and Huey who benefit greatly from having so much of their backstory explored. The unusual friendship they form is one of the highlights of the series for me. Huey's friendship with Elmer, along with his love for Monica, ends up humanizing him a great deal.
Also from the 1711 immortals are Nile, Denkuro, Sylvie and Victor who get negligible screen time in the anime but are greatly expanded on in the novels. They all deal with their immortality in different ways. Denkuro spends years trying to go home but when he does he finds everything has changed. Nile fights in war after war, Sylvie is cursed to spend her endless life without the person she wanted it for in the first place. And Victor seems unaware that he's in a Narita novel as he decides to devote his life trying to force order and harmony on the universe. I love reading about all of them and while they may not end up being your favorites - you will have favorites. This is a cast you'll end up feeling attached to.
Enjoyment 10/10
I don't think it's possible for me to enjoy this series more than I already do. There are so many great moments that more than make up for slower sections of the story. The hardest part is dealing with brutal cliffhangers that don't get addressed again until many novels later thanks to the timeline jumping around. But every smack down and wham moment makes it all worth it.
If you have any curiosity about the series it's well worth trying out.
