As for the triangle, nothing is really resolved - it looks like they are going to keep us hanging until the next movie. The preview image at the very end implied as much - both Ranka and Sheryl in wedding-like outfits (not really gowns though, but lots of white lace).
The triangle doesn't get as intense as the series - not enough time. At the end, Sheryl, tells Ranka she wasn't serious about Alto, but it is obvious, to the viewer, if not Ranka, that she is not being truthful.
Sheryl definitely spent more time with Alto in the movie than Ranka did, although as I mentioned, the movie started out with Ranka and Alto already knowing each other.
The battle scenes looked good, and the theater shook with the sound effects. However, there wasn't as much individual combat highlights as in the series, almost none in the space battles actually. The initial battle where Alto saves Ranka, is almost exactly the same. There are two other major battle scenes after that are different from those in the series.