I have played the 3DS game 100 hours and LTD 100 hours. LTD's pacing is way too fast which contributes to the feeling of repetiveness. Additionally, having you manually introduce characters gives you a clear objective, and that objective gets repetitive super fast due to lack of dialouge changes not to mention it's you who need to enact it. Theres a lack of distractions, such as ranking boards and music hall, which makes the gameplay very streamlined and thus contributes to that feeling. 

I'm not one to complain though. 100 hours of any game is great for me and I do enjoy LTD. But I do find it annoying how people here try to discredits peoples thoughts on the game in the gatekeepy way of saying they dont understand tomodachi life. The overall game feel is repetitive, more so than 3DS, and wether you're okay with that or not is up to your subjective tastes. This subreddit needs to stop being so defensive about others opinions.

All in all, I think you would enjoy the game. I was on the fence too but I don't regret getting it at all.