I finally got around to this last week and wanted to share my thoughts!
(+) Accessibility - There's so much PnP material around Root that if you have the base game, it's very easy to try out the other factions and the bots. A file is available on our game page as well, except that it's based on version 5 I believe, which I think is one version behind the official published version. The updated boards for the bots can be found here: https://www.dropbox.com/sh/iq4rp6pwdntvh1c/AAC6S2-lj_KLclFb4MaxCUXWa?dl=0.
You just need to print out the faction board and difficulty level cards for the bots. The bots use the same token as their non-bot counterparts, so there really isn't a need to buy #Root: The Clockwork Expansion unless you have some cash to spare and want the official set. For me, I'm leaning toward getting #Root: The Underworld Expansion next year and just settle with the PnP for now. Will see where this goes after I get to play some co-op with my wife.
(+/-) Rules - The rules are simple and short, but I personally had a bit of a hard time interpreting the nuanced language and was left unsure whether I'm making the correct moves for the bot.
(+) Gameplay - Ever since I started soloing games, I've come across maybe 3 or so different types of solo modes: "beat your score"-types, "hazard"-types, an an actual AI opponent. I enjoy the first two types for the puzzle solving fun provided that it doesn't require so much setup, but I often settle for an app experience. Root falls under the third and it's my favorite type (#Architects of the West Kingdom's solo mode is pretty close to this too) because it really stretches my muscle for strategical/tactical plays, I get to explore different factions, the AI opponent does a great job of simulating a real opponent, and there's a good amount of luck in combat and card draws that make it exciting.
I especially like what they did with the bots for two scenarios: (1) when a bird suit is drawn from the order card and (2) when the bot fails to execute an action in a turn. For the first--bots execute actions based on suit of the "order card" drawn for its turn. The bird suit is a "wild" in Root, and is valuable to many of the factions. So when this suit is drawn, the bot goes through an "Escalated" phase where each of its actions are more powerful. For the second--there are occasions when the bot has "Recruited" all of its warriors onto the battlefield that it can't execute the "Recruit" action as part of its decision tree (or times when it can't "Build" anymore on a particular suit of clearings because they're full. Rather than making this a safe turn where the bot would essentially give you a free pass like in most games, Root just makes it more challenging because this reflects the human opponent's failure to adequately suppress the bot. This essentially leads to the bot taking action A, B, C, failure to execute D, go back to the top and execute all of the actions again based on a different criteria. I'm not sure if this makes any sense for you, but it sure is tough and simulates how you have to constantly keep your opponents in check in Root.
TL;DR: This is my favorite solo game now! I played as the Eyrie against the Mechanical Marquise and won a close game of 30-24. After trying out Marquise vs. Electric Eyrie, I'll probably go with the Woodland Alliance against two bots! :)