I'm a big fan of the series and would consider it to be my favorite JRPG series, not just for the story but because I enjoy the gameplay it offers as well.

It's a fairly "cheap" series to try out and see if you're into it. The entire series is a singular, continuous story, so the recommended place to start is Trails in the Sky First Chapter, which can be picked up fairly cheaply on Steam, especially during Steam sales. It's not as long as future games in the series, and is fairly representative of the pacing and storytelling format that later games will follow (though it is considered one of the slowest-paced games in the series). Basically if you're not a fan of Sky FC, you're not likely to be a fan of the future games in the series either (especially given that the substantial improvements to gameplay over the series' 20 year history likely won't have much appeal to you).

There are also demos available for some of the newer games in the series (e.g. Trails of Cold Steel III), and while I would not recommend actually playing through those games out-of-order, they may serve as a quick/cheap way to see if the format of the games is right for you.

I will say that while the combat of the games is rarely very difficult, and the game provides difficulty modifiers to make it even easier if you'd like, that the combat system is still fairly fleshed out and quite good casually IMO, but if you're really not into doing it even at easy difficulties, one option (PC exclusive) may be to download completed game saves and play through the games on New Game+ and completely trivialize the combat.

I'd say that is accurate. It is a slow burn to start, and it took me several tries to actually get into it. Once I did, I ended up plowing through all of the games. :) They are all excellent. The series is really something special. Trails to Azure is actually one of my most favorite games of all time, too.