Age of Wonders games are much more focused around tactical combat than typical 4X games. The emphasis in Planetfall is researching both unit types and mods and customizing your armies to take a certain approach to how you will fight on the tactical screen. At heart it still retains the AoW formula of a medieval feel with fortified cities with a big army marching around, and the optimal strategy is usually to bulk up somewhat and then march on an enemy capital and have a big field battle to try to kill the enemy leader. Then you take the capital and that faction is out and you get all their stuff, which doubles your economic power. Very different from a game like Sword of the Stars or Master of Orion II where you really can't capture enemy planets, you just glass them, or Warhammer Gladius, where you can't capture enemy cities, just destroy them, so there is no power surge from knocking an opponent out. This is more of a "the Turks take Constantinople and now they're twice as strong as before." Like I said it feels ancient/medieval with the climactic field battle and then mopping up the cities.
Of course on higher difficulty levels it can be entirely different because you might be getting attacked from all sides, which prevents you from concentrating your forces in one spot and delivering a knockout punch.
If you are autoresolving major battles you are missing the point of the series. It's a tactical battle generator.
Planetfall does add jobs and sector development which tends to give it more of an economic dimension than AOW3. However it also makes all the factions feel the same strategically, like they do in Civ, because they all have more or less the same relationship with the physical environment. No more morale differences based on terrain etc. No differences in habitability based on race like in an outer space 4X. An energy sector is an energy sector no matter what faction you are. It is possible to micro the build order and the jobs to increase your economy and research speed and pop growth, and maybe it's necessary at the highest difficulty levels. For me that's not the point of the game, I prefer a lower difficulty level and just enjoying the cool fights and exploring the sites, getting unique weapons and mods, etc.
For me the magic combo is Amazon Xenoplague, which lets you get both laser-firing tyrannodons (which are just incredibly fun) and Plague Lords (which look like a cross between the Dunwich Horror and a Martian tripod from War of the Worlds). These are fun cool looking armies. The Xenoplague aspect, like being a Necromancer in AOW3, makes you want to infect enemies before you kill them so you get more/better Xenoplague units, so the battles become a more interesting dance than just "focus fire to kill." A lot of the other factions/techs left me kind of lukewarm.
Some of the environments are kind of ugly (like Arctic, but this is true in AOW3 as well) but many, like Arcadian or Fungal, make for really cool looking battlefields.
Ultimately it is not a game about microing your empire, it's a game about tactical fights. The emphasis is much more on range (though the expert players lecture me about how good melee is in competent hands) than in AOW3, but it still is a giant army moving around to take on the enemy giant army and then take the fruits of victory - very much pre-gunpowder in feel. It rewards aggression, knocking out an enemy is a much better way to increase your power than building up your own carefully groomed cities.
If you want to fiddle and fuss with your own empire like in SMAC to the point where you can win from just turtling, it's not for you. In theory you could do it in PF using Doomsday Weapons, but I am not sure what the point would be. The fun is in the battles. Unlike AOW3 the battles feature a ton of status effects so much of the battle will be inflicting 4, 5 or more continuing effects on enemy units (not an exaggeration) while trying to dispel the ones they inflict on you. "Stagger" is a crucial aspect of the game. Remember those Throw Curse attacks in AOW3 where even if you resisted, you lost an action point? That is a mainstream effect now in PF, and a lot of the game resolves around inflicting Stagger on your opponents so they lose action points/defensive modes, and adding Stagger Resist to your own guys to try to avoid this happening to you.
There are different defenses like shields (ignored in melee) and armor (ignored with psychic attacks) and resistances to certain damage types, and a lot of mods/attack types/"spells" whose purpose is to lower these enemy defenses so they take more damage when hit. This is actually pretty interesting on the tactical battlefield and in unit design - with 3 mod slots per unit, which ones should go to defense and which to offense? The problem is all races and factions pretty much have the same set of concerns - maximize your defense while eroding theirs - so like the economic game, it creates a certain genericness. This biochemical mod melts an armor point per hit. So does this laser mod. Are they really different mods?
If you play Amazon Xenoplague and you like cool units you will have a good time. Any other combo - it might be quite effective, but it won't be as fun or cool, IMO.