After a pretty uninteresting Sailor Moon R (with the first 13 episodes being a filler to wait for the manga and an annoying chibiusa), this series is a relief. The new characthers, Neptune and Uranus are pretty interesting, in opposition to Chibiusa's addition in R. There is a purpose for them being there and a nice arc of development.
But at some point, the series gets very boring. The episodes are pretty much the same, with obvious messages like "the power of friendship" and the same structure in every episode. This screentime could have been used to focus on the inner senshi, that just got some attention in the beggining. Or mix with some school life moments of Usagi. Naru and Umino just disappear. There is almost no development on the charachters as "common girls".
The last thing I'd like to highlight here is that all the final action happens in few episodes. The climax could have been extended a bit more, to explore better the closing stages.