Inventors is easily the most complicated Garphill game I've played, and I really enjoy it now that I've got a few plays in. It took a few tries to make sense of all the rules and options, but might have been a little easier if I'd watched a how to play video rather than just stubbornly learning from the rulebook! It is well worth the time to learn how to play and how to make sense of the iconography. The mechanic of costs and benefits changing on each invention, depending on what action you're doing or what stage the invention is at, is confusing but cool. There are many things to juggle and many different things you can focus on for the endgame, which I really love in a game as it means there's not just one particular path to victory.
The theme is fun and well realized.
I definitely recommend this one, especially if you enjoy the other South Tigris games.