So, having run it with some modifications (I posted my PDF somewhere on this site), here's my take:
It's a pretty good sandbox. I really enjoyed the little tasks around the keep as a way for newbies to learn to RP and get the hang of basic abilities at Level 1. It kind of feels like a starter zone in World of Warcraft; you can almost see the little exclamation marks above the NPCs. I think the wilderness areas are done well, also, with a cool variety of encounters and a fair amount of stuff to find.
There's very little plot to the whole thing, and I found the Caves of Chaos are to be kind of goofy; ultimately they became tedious. The densely populated caves all being within a few dozen metres of each other made no sense to me, so I added a more cohesive story and spread the caves WAY out; in my revamped version they are part of an old complex spread out over several kilometres. I cut out a lot of encounters and made many of the caves even easier to find RP solutions, because there was a bit of a repetitive vibe otherwise: go in, do 3-4 simple fights, roll on magic item table. ***
My biggest change was really beefing up the plot around the "Cult of Chaos" so that they became a Cult of the Chained Oblivion and tighening up their plot to attack the Keep by recruiting some of the denizens of the caves; I also made several of the Keep NPCs secret cultists to facilitate this plot. And when the party finally moved on the cultists but decided to take a long rest after an early encounter, I decided that the Cultists would speed up their plan, so the party found their HQ empty and had to rush back to the Keep to foil the cultists with a pitched battle in the Keep itself. This made for a more pleasing capstone to the mini-campaign, IMO, and easily segued into the next set of adventures that I designed.
So overall I liked it. The resources on DDB are very good, and the framework was enough for me to easily expand into something meatier, which is my personal preference. But you could also run it as a very direct, old school-type campaign as written. It's not Lost Mine of Phandelver or Frozen Sick tier, but I would put it in my second tier of starter adventures.
***Note: I was using it in a campaign with a lot of beginners, 14-17 years old, and our sessions are typically 1.5-2 hours after school, once per week. Combat is slower in D&D2024, especially with newbies, because they have more options to wrap their heads around, so I prefer one meaningful battle per session, on average, rather than a bunch of little fights. I never have more than two battles in an after school session, and sometimes there are none. So 3-4 fights just to clear out one of the tiny Caves of Chaos subcomplexes was not working for me.