I'm a few hours in. So far it's Warband with a Viking-era coat of paint ... so, it's fun! Nice to have a storyline providing (optional) structure to the standard sandbox. But it crashes to desktop at least once per hour. Hard to recommend. I've had nothing gamebreaking, it just requires restarting the game ... which makes the load times annoying. So you'll want to keep your finger close to the quicksave, and be patient. Playing on mac.
It's not perfect. The combat is slow (on Normal difficulty: the enemies dies much quicker on Casual) and feels like a chore at times. It gets repetitive. But I found the gameplay loop (level up and equip survivors, go out and kill zombies, craft stuff, level up and equip survivors, go out and kill zombies) quite addictive (in a fun way) and the story events and character interactions kept me interested. Some of these are randomised, so there's replayability, and each new character starts out a bit stronger than the previous one due to upgrade points you'll earn. I found all this very engaging. It ran smoothly: no bugs in my playthroughs. Some of the mechanics aren't clearly explained but you'll figure them out over time, especially if you look through the "Equip" and "Gear" screens early on. Many of the enemies, items, skills & stats have an info pop-up if you hover over them. The game's by no means broken or mystifying.
The store page was full of 2015 reviews saying the game didn't run on Windows 10. It does now: I just installed it and played, no patches or settings tweak necessary. Looks like GOG fixed the problem. That aside, the game's really fun. It plays a lot like Jagged Alliance or combat in the older Fallout games, so if you like those you should buy it. The UI's slightly clunky 'cause it was built to 1998 standards, but it all works except that the map sucks. The story's boring, but if you rename all your space marines after family and friends you get 50 microdramas to get engaged in. The music's good but overly repetitive. I'm having a lot of fun with it.