The synagogue had both the Friday night and the Saturday morning siddur available. Unfortunately, I didn't get a good look at the Friday night one. I remember seeing what seems to be an earlier edition of this siddur, though, in the form of Friday Night Alive! GJC, as far as I know, still uses their copies of this siddur every Friday night, even years after they got them for the purposes of "Setting Philadelphia Dancing". I have no recollection of this series of services attended by 800+ people in Philadelphia. But I do remember the siddur being pretty good, especially for something that came out before the Purple Siddur.
On the other hand, I managed to get ahold of Singlish's Saturday morning siddur, the aptly titled Shabbat Morning Siddur, and was able to use it for davening. It certainly had some features to recommend it: The three-column format (Hebrew, English translation, English transliteration) does go a long way toward making services more accessible. The decision to use more modern translation was often fruitful. The footnoted commentaries and text references were insightful, though they are likely to suffer from the same problem as commentaries in other siddurim; namely, that they get old after reading them every week.
However, the siddur is quite lacking from a usability perspective. The same alternative typeface, quite distinctive from the primary font, is used for both non-traditional additions of words and phrases to the liturgy and for parts of the liturgy only recited on certain days (such as holidays or Shabbat Shuvah). This was quite confusing; my preference would be to use an alternate typeface for the nontraditional additions but a different-colored background for the day-specific passages (the one thing the Harlow mahzor got right...sometimes). Also, the small page size made the columns way too narrow. It's very difficult to read a Hebrew passage of any length when there are never more than two words per line; the Purple and Yellow Siddurim's 4 columns spread over two facing pages, by contrast, are much more readable.
Finally, the page number comparison chart in the back of the siddur was quite the nice touch, but the fact that only the old Sim Shalom, Artscroll, and perhaps one other siddur are included makes the list almost useless. Most Conservative synagogues have the new Sim Shalom by now, and many other places that might be interested in this siddur currently stock older Conservative siddurim, Gates of Prayer, or Kol Haneshamah. I can't imagine, therefore, that this list is of much use to anyone. The omission of the new Sim Shalom is particularly bad, just because the page numbers almost but don't quite line up; thus potentially confusing those unfamiliar with services even more, unless this siddur is used as a primary siddur somewhere.
But the worst feature of the siddur grows out of one of its best. The modern translation goes too far. At least the author acknowledges that his siddur will be out of date even 5 or 10 years from now, as modern terminology grows and shifts. He is unfortunately right on the money. And the word choice is already questionable, less than a year after the publication of the siddur. As soon as I read that the first word of the translation of Ein Keloheinu was "Ain't", I gave up on the siddur. There's readable, there's modern, there's accessible, and then there's using slang for slang's sake. "Ain't" does not convey either the direct meaning or the feel of the wording of this prayer, and this attempt turned me off to the entire style of translation throughout the book. As someone whose Hebrew is still shaky, I prefer the most literal possible translation, so I can try to learn the nuance and idiomatic tendencies of the original. I can see the value of a more poetic translation if it does a good job conveying the sense of the original, but this one does not.
Making matters worse, my synagogue president decided to introduce this siddur to the congregation as a good siddur to use for remedial congregants who can't keep up with the service. Not only will this presentation effectively keep anyone from using the siddur at all, but it happens to be much harder to use for a beginner than the new Sim Shalom, especially if the page numbers of only the latter are being called. This siddur's only hope in synagogues is as the primary siddur of a congregation, and at least in the case of Saturday morning, I hope we don't adopt it as such. More likely, it'll be used only infrequently, and will drift to the bookshelf at the back of the sanctuary, to live next to the old Sim Shaloms and Birnbaums and Artscrolls that are also rarely touched.