Phantom Arc starts off as a trip down memory lane. It has been 24 years since any of Chirico's friends appeared, and seeing their banter and hijinks is an instant reminder why they were so important to Votoms despite their minor relevance to the plot. To drive the nostalgia home even harder, the first two episodes deal with revisiting the planets of Uoodo and Kummen in search of Chirico, who we are told has visited them since the events of Shining Heresy but left, as is later portrayed in Alone Again. Gotho, Vanilla, and Coconna treat their return to the ground of Votoms' first arcs
very much like the audience might, and the creators likely do, noting all the peculiarities of their old environments and the way things have changed or remained the same.
But from there the story picks up as the trio is driven into the background, and a curious mix of the old narrative with new elements forms the meat of the story in episodes three to six. While more votoms is never a bad thing, it's quite clear that the initial direction taken was judged to be a mistake, and that a more serious approach was necessary for what is currently the last chronological entry in the franchise. The fact that there's only about four episodes to execute this more complicated plot is simply a mistake. While the nostalgia factor continues throughout the show, the plot just doesn't really hold up even when it tries to do something interesting.
One net positive is that the creators have learned from Shining Heresy, by incorporating some elements from it without taking in any of the boring stuff. It doesn't make the plot better exactly, but by acknowledging that it happened Chirico's current status and journey feel a lot more valid. It's not inconceivable from a story perspective that Votoms could one day be continued, and Chirico's path has become one that is interesting just by it's sheer length both in and outside of it's universe.
The CGI has stepped up quite a bit from Pailsen Files. While it's far from flawless, it's never openly painful to look at, and there's occasional good use of what CGI has to offer in terms of quicker animation than hand-drawn frames ever could. That being said, Chirico himself doesn't get into all that much scopedog action for once, and with the limited amount of time the focus is much more on the plot.
When you get down to it Phantom Arc is a retread of old Votoms, and your enjoyment will greatly depend on how much you care about seeing Vanilla, Gotho, and Coconna again, as well as your interest in some of the ideas from Votoms' Quent arc. Anyone who is a fan of the franchise at least owes it to themselves to watch the first two episodes for nostalgic purposes, and perhaps the rest to see the current conclusion to Chirico's saga.