If you find the monsters repetitive, try getting their Monster Info for your student book and read their individual descriptions. Some are more memorable than others and some are palette swaps from yet others. The same could be said about any series, though.
In terms of dungeons: what you've seen so far takes place in the same building, so it's not surprising they look similar to one another. There are a couple of more areas to go through in that same building, and, equally unsurpisingly, they make use of the same textures but different gimmicks. Dungeons outside that building have their own textures, but are not by definition more interesting. I personally do find them interesting, but that's because I can draw comparisons with dungeons or patterns in the other games in the series. So while the dungeons get slightly more interesting visually than what you've seen by name, it never reaches the levels of the games you mentioned -- those are games created with far larger budgets, larger teams and with more time than Trails of Cold Steel put together with.
Seeing your nickname and avatar, however, I really encourage you to overlook the game's visual flaws and endure until the game's political dimension comes around.
