Main Event is clearly an earlier piece given the prevalence of "Unseen" mechs as prominent features in the story and just the overall story tone. I think every other Battletech novel at the time was about a new mercenary company getting started as this was the most common entry point for people playing the RPG or the first video game.
But this is also a post-Clan novel that takes place during that pivotal period after the Truce of Tukayyid. It doesn't get to play around during one of the big historical moments of Inner Sphere history that involve members of the Great Houses and instead is something is very focused on a much smaller group of people.
Synopsis: Main Event is Battletech science fiction novel written by James D. (Jim) Long and his first for the franchise. The book introduces the Black Thorns mercenary band into the fictional universe, although they have also appeared in various source books for the RPG.
The story is primarily told from the perspective of Jeremiah Rose, a former Com Guard Mech Warrior who became Dispossessed of his Battlemech during the battle of Tukayyid. He returns to his homeworld of Northwind (home of the Northwind Highlanders mercenaries) in order to petition to form an independent mercenary unit that would take jobs in Clan occupied space to take the fight back to them. However his request is denied and he ends up creating a unit on his own with his sister Rianna being his first recruit.
The plan starts out with two major phases - first "Rose" has to journey to Solaris VII in order to find a Battlemech to purchase and perhaps recruit a few warriors to his cause as well. His sister, acting as his XO, will journey to Outreach in order to get their new mercenary band registered and to start the recruiting process along with hopefully finding a contract as well.
What I Liked: It takes a while for things to get started but the actual battle once the group gets its first contract (in the last third of the book) is actually pretty good with some fun moments and a lot of classic mechs featured in the story. The rough terrain of the planet makes for some nasty close-up fighting, which seems to be the bigger focus of the book's combat scenes.
We have to note that the bulk of the combat involves Inner Sphere battles and not necessarily against the Clans. It's a bit of a small miracle that they survive their final encounter with the Clans but on the whole they weren't too bad with what they had to work with. Makes for interesting reading.
What Could Have Gone Better: The entire book is told from Rose's perspective, and yes the narrator mainly refers to him as Rose during the book instead of Jeremiah. But the way events flow seems a little shaky, like the author was given a checklist of moments in Rose's bio that they wanted him to address and he just had to make the most of things. We see little character development for the people around Rose and instead they're more like pawns subservient to the needs of the plot.
And there are gaps even for Rose's story, like how exactly he managed to afford to create a merc company in this manner. Sure the book spends some time on Solaris (although the cover would want you to believe that this is the focus) and he does the classic "I bet on myself" gamble to get money, but most of that goes to purchasing a mech. So how did he have the leverage to convince folks to sign up for a new group with no contracts?? Questions like this nag me throughout the reading.
TL;DR: Main Event is almost stereotypical early Classic Battletech fare given the struggling new mercenary company and their first big battle at the end. It's not the best example of this sort of book but it tries really hard and you have to appreciate that. Thus the book gets 3 odd relationships that Rose manages to foster out of a possible 5.