Green Star is very forgiving with cutting and weeding - great for we who are new to the business. The "type" of vinyl it is, is not one that will last that long - read up on calendared VS cast. All off this info is already available throughout this forum, other forums, and specific vinyl websites. Color longevity will also be an issue.
The short answer is: Yes, on some window applications. Most people do not apply it to the painted surface of autos (again, calendar/cast - this calendared vinyl tends to separate and crack over time, thus creating a potentially disastrous or damaging removing process later). I have used it some on MY windows with success ( 9 months now - WHITE), but have moved to "other brands" for most things and always for a paying client. (I can change out my own applications any time it starts to look less than crisp). I reserve GS for short term items like banners and coroplast yard signs. Colors you use often, you will always have fresh rolls of "good stuff" on hand. So, as you "mature" in this business, you will find what best suits you and the jobs you get, and you will develop your own opinions as to vinyls. But remember, your reputation and future business is riding around town on those windows, so develop those opinions wisely.