Page 121 does a good review:
Thanks (I actually already bought it yesterday night, I'm not hard to convince, especially at that price ^^ )
There are a couple misconceptions in this video that needs clarification, I think, in case anyone is considering trying a solo game with this book. I'm not blaming the youtuber for it, he clearly states he's not experienced in soloroleplaying.
1. you can't be surprised in a solo game
That's not true, quite the contrary! I haven't yet read SOLO so I'm not sure what's the extent of the tools it provides, but from skimming through it, and from this video, I saw it has an oracle, which is all you need. If you're used to be a GM, it's easy to get lured into deciding of a whole narrative arc in advance, deciding the secrets of the NPCs, the lore of the place, etc, but it's exactly what you should not do. Instead, you play as a player, knowing nothing about the place you're visiting, and you ask questions to the oracle about it. Is it crowded? Is there someone noticing me? Is there a lot of security activity around? Etc. On top of that, in Mythic, we have elements tables, which are you regular RPG table, but with more vague words in it, more like concepts. You roll twice on it, then interpret the result through associative thinking, the first thing that comes to your mind. For example, I walked in that startport and the oracle told me that yes, someone noticed me. Who are they? I roll on the character identity table and get the words "Persecutor" and "Explorer". My first idea is that it's some sort of bounty hunter (yours was probably something else). Maybe they mistaking me for someone else? Is that person making an hostile move toward me? That's an other question for the oracle, but in just a few rolls, here is your surprise, and it never stops.

Actually, solo systems are all about introducing surprise, they have many mechanisms for that.
2. Why play solo? Because you have nobody to play with
I have people to play with and I still very much enjoy playing solo, it's neither a consolation price, nor exclusive (you can play solo game _and_ an other game with a group). You play solo because you want to have it your way, because you want to play a game or setting your group is not interesting in, because you want to develop the lore of the group game, because you enjoy the solo mechanics, because you have 5 minutes on commute or before bed time and you can afford to play just 5 minutes in solo, because you're tired of the lack of freedom in your videogames, because you just like telling emergent stories, etc. It's a whole different beast, it's not meant to _replace_ playing with a group. Although, of course, if you don't have a group, it's a good way to not have to give up playing a game, but it won't be the same thing anyway.