The representation of company, platoon, squad/section, down to fireteam, is accomplished brilliantly in SL:PL. From the game perspective, the coordination of your models within each element of organization is a huge tactical draw for this rules set. For example, activation of a single squad has the player moving and acting with the fireteams within that squad, which gives the sense that the choices are being made for a small "army within an army". This is when playing with individually based models. The rules also support stands of miniatures for the groupings, but playing with individually based is where this feeling really shows itself. Though the teams act as one unit in terms of their actions, there are still enough tactical options within this framing that it does not feel like a "line them up and shoot" game. Though i am a fan of games where individual models may act on an individual basis (e.g. each model in a unit can target whatever they desire, etc.), I enjoy the balance that SL:PL gives between that and models acting in a cohesive, team fashion.
The morale system is a real entity in the game, not just a tacked-on, obligatory dice roll with a single consequence. Morale is modelled in a way that can hinder teams within a squad to various degrees, from simply reducing available actions to rendering a team almost ineffective until a rally can be achieved. It is all handled with a simple dice roll algorithm, no lookup tables, which is really nice for game tempo once again.
The way defense values for infantry (and some vehicles) and armor values for vehicles (and power armor, though power armor has a defense component for some situations) are used makes each mechanic have its own weight in the gameplay. Firing any weapon vs a defensive opponent ends up having a very differently flavored outcome when that same weapon goes against armor. SL:PL really shines here, making the combat action feel right, depending on what weapon is being used vs which target.
The abilities for both infantry and vehicles feel right on. For example, i have disliked how Active Camo has been handled in other rules sets, but here, SL:PL hits the nail on the head. Same goes for support weapons. I LOVE that flamethrowers and grenade launchers are implemented without the need for AoE templates but still work beautifully; the game tempo thrives from this too. Mortars still use an AoE, but rightfully so in their case. Oh, and power armor feels like POWER armor, without being game-breaking. The game details many types of cool tech and specializations, so any type of unit can be created pretty much, with as much simplicity or complexity as desired. There are pre-generated teams in the rules and online, so no need to fret if someone wants to plug and play.
Oh, and unit creation SHOULD involve math. I have read reviews that seem to complain that one needs to think too much to create units in SL:PL. The amount of crunching needed is nothing that someone who should be able to calculate probabilities cannot handle (looking at you, wargamers:-)). It's simple arithmetic here, and there are great running examples as one goes through the process. And how the values are generated for team attributes makes good logical sense.
There is so much more to SL:PL that i could go on, but these points i have made are the things that really drew me in after my first read of the free introductory rules. I purchased the pdf right after and have not been disappointed.
The only negative items to note for me have been these: 1.) There are multiple rules for rounding fractions for various situations, and multiple required criteria for dice rolls (i.e. it is not just meet or exceed a target number as a general rule). While these would become 2nd nature the more it is played, it still makes for some rules digging in many situations. The author has done this for a number of good reasons, so it is forgiven overall. 2.) There are some discrepancies, typos, and mentions of rules without any formal description anywhere. Luckily, Karl is really good about answering emailed questions to the address on the Legionnaire website. I am hoping a true errata/FAQ might be released at some point (but that requires more people to start playing this game to generate the interest!)
Final thought: I am surprised that SL:PL is not a more popular game, especially in the 15mm arena. It has a nice balance of simple mechanics with enough "crunch" that should please anyone. Though it is a company level game at its largest, it can be tailored anywhere from single fireteams to that level with no issues. I know most of the current rules sets out there currently, and though SL:PL has been around for a bit, i hope that more interest will be generated for it, especially with the love for 15mm scifi happening as of late. Many of the great minis available now fit into the game perfectly. Highly recommended.