Shadowrun Returns is a mix of RPG with Turn based combat. The RPG aspect of the game is very complex, you got all sorts of skills to level up, magical: like spirit control, chi, conjuring, spell casting; combat: like melee, dodge, shotgun, machine gun, strength. decker type and/or drone control like. Depending what path you choose you could master one of the five or four classes that the game has, Shaman, Mage, Decker (hacker), Drone Expert, Samurai, (and there are few more). Then if you want, you could refine that even more you could create a Mage that's has expertise in ranged weapons (for example), or a Decker (hacker) that it's also a Shaman. Also you got other skills (none combat based) that are important for interacting with elements and talking with NPCs... Shadowrun, Decking, Socialite, Corporate, etc. Those skills are very important in some levels it makes the mission a lot easier. Sometimes with those speaking/hacking skills you could make an enemy surrender, make a smart computer open a locked door or make an enemy leave the battlefield instead of having to kill it.

Apart from your character which can be any class of the ones mentioned, (shaman, mage, etc). Also it can be an Orc, Elf, Human, Dwarf, etc. This also have some impact on the skills tree, some races have more resistance to melee combat and other are more skilled in magical aspects. So a character can be very complex.

In the first missions you are alone but as the game progresses you have to assemble a crew. A good hint is always to have a decker, hence some missions can't be even be completed without it. ( In other versions of the series some mission require a drone expert). Most of the mercenaries (shadowrunners) cost money some of them are free but just 1 or 2. I normally carry a Decker, a Samurai or combat expert and another Mage or Shaman. Some ppl play different styles because there is plenty of possibilities on how to finish the mission, that heavily depends on your skills and also on your crew.

I chose being an Elf Mage, with Mages you can summon spirits that are like dummy warriors that have a limited lifespan. And Elfs have better bonus points in spirit control and spirit summoning.
On my crew I like having another mage/shaman also that can summon spirits makes combat really easy because instead of having 4 characters on the battle you have 6, it's a killer advantage. But there is catch summoned spirits spells and other casts are really expensive, (at least the ones that are powerful), so you have to do some side missions to earn enough money to be able to buy enough magic weapons/spells.
You might choose another path for example when I played SR Hong Kong (the first of the series I played) I chose combat samurai. Maybe that's what you should choose if you are a newbie to the series, imho is much more simpler only reload the weapon, take cover and fire.... but remember to supply yourself with a LOT of medical supplies (maybe you could carry a powerful Mage/Shaman that has healing capabilites also).

At the start you will find yourself dying a lot, the game is not that difficult but yes it's rather complex. I really didn't fully understood everything till I finished SR Hong Kong (which was the first I played). But once you master it if you like RPG/Strategy games it's very satisfying.
Then there is the story. Prepare yourself to read a lot. It's an important part of the game sometimes NPC's will give you hints to earn cash or acquire items. The first time I played the Hong Kong version I practically skipped every dialogue because it can be really tiresome. That made the game a lot more difficult, because I was short of cash. But anyways if you are the kind of ppl that don't like reading you can skip most of it, it is doable.

Overall I think is a superb game with lots of depths and complexity, I think that maybe some day I will play it again. Also there's quite a lot of replayability because depending on the character class you choose the game is different also what character classes you carry on your crew changes the game. But the enemy AI in the combats will mostly do the same thing there also a lot of scripted combats and environments ... so it has replayability but to some extent.

the only issue I found is like many games it doesn't disable compositing so if you have a screen edge set up to trigger a desktop effect it can bother sometimes.

Played on KDE Neon 5.17.3 (Ubuntu 18.04 based). Mesa-dev 20.0 ACO valve drivers.
CPU Ryzen 2600. RAM 8GB, GPU Radeon Rx 570.