If you don't know jack about Union Jack (sort of like me), this is a pretty good introduction. It introduces the new Union Jack, what I assume is going to be his nemesis and gives you some back story.
What I didn't like about it was that the pacing was off, in my opinion. A lot of new comics will build up and spend some time on the character's history, emotions and motivations. It has been an important part of their evolution. In this TPB, you get all of that in about three pages. That is what comics used to be like...and it takes away from what could have been a really great story.
Still...it was a fun enough read and if you fill in the gaps with your imagination, you should enjoy it well enough. If would have given it 3.5 stars if I could figure out how to do that....