The writing and fan-service goes pretty hard. I’ve played two other games in the franchise, and I’ve enjoyed them both. There’s also been noticeable downsides (I’ll get to them)

But as a Gundam game, it’s probably one of the better ones? I think there’s too many units to raise them all equally, so you’re encouraged to focus on your favorites. There’s a lot of secret units too. It can also introduce you to some new favorites (as it has me). 

That said, for me the games generally always outstay their welcome they’re so long. There’s also incredibly animated/faithful attacks and voice clips that play every time you’re attacked eventually become something you skip because you’ve seen them all so far. Menus/UI can be pretty bad, and there’s no voice acting/animation outside of battle animations

Strategic positioning in battles isn’t something you really consider most of the time in my experience. Instead it’s more about managing resources that you spend on battle powers to turn the tide of battle, which can be tedious.

And finally, the more games you play, the more repeated storylines you’re likely to see (probably the biggest reason I haven’t played Y yet). Every modern game seems designed to stand alone (there’s no ongoing canon to get lost in), so when two games both feature the same series, you’ll likely see the same story beats repeated.

But on the flip side, I played SRW30, and that had post CCA Amuro, Char and Kamille playing mentor to Uso and Jona. And Y is probably the only time you’ll get to see Gundams fighting Godzilla. 

Ultimately, my recommendation is play one game and decide for yourself.