ARK is one of the best Open World, Sandbox Survival games out there aside from Minecraft. The experience you have with it only depends on how you set it up. In it for a story? Want to dominate other players? Want to enjoy creative building or fancy the challenge of taming all the creatures and breeding up the best tames possible? You got it.

Do you want to RP? Do you enjoy solo gaming?

All of the above is possible just with the vanilla game and then the mods come into play. From QoL additions to total conversions, the possibilities are limitless.

There are 6 story maps + a handful of officially supported, fan made maps. And then the mods...
You can enjoy them in sequence or play on a cluster where you can travel between them making use of the characteristics of each.

As with any complex game, you will inevitably run into silly bugs, wonky mechanics and other annoying things however they are few and far between as long as you stay 100% vanilla.

Fan made mods definitely make the game a bit more unstable but the workshop ad its ratings can help you decide what's worth it.

Ark's biggest drawback is the developers' attitude which is ever changing but never been more than... lacking.

Regardless, the end result is a gaming platform that can give you the experience you wish to live given you learn how to make that happen.

Is it worth the full price with all the season passes?
Categorically yes. A lot of the community boasts with multiple thousands of hours spent in game which makes it one of the cheapest games ever when you calculate how much you pay for 1hr of gameplay.

However

There are very frequent and big discounts.
If you like survival games do yourself a favour and pick the game up at least when it's on sale.

What should you buy?

The base game will give you access to the first story map + some free maps that aren't involved in the story.
To fully experience the arc of the ARK, get the Season Pass which gets you all the maps that are involved in the first story completely.

The Genesis Season Pass gives you 2 new maps that host an independent story line. I recommend getting this only when you are bought into the franchise.