Though I haven't read it recently, I enjoyed Episode Zero during the days when Gundam Wing was playing on Cartoon Network. It was a great prequel to the series, giving insight to character histories.

I’m a sucker for character’s backstories and tie-in expansions for worlds I’m already a fan of, and this book falls smack dab in the middle of both.
You get to see the pivotal moments that make the Gundam pilots who they are and how eerily connected everything is in the Eve Wars.
The reader gets to see how Heero got his name, how Duo got his braid, Quatre’s silly goggles are explained, Trowa´s mercenary background, and why Wufei refers to his Gundam as Nataku. Everything is capped off with a quick peek at how the pilots save the day with Preventers after the wars are over and they’ve gone on to live their lives.
The art is clean yet detailed enough that you really get to enjoy the mobile suits and the world they inhabit. The writing is pretty good and to the point.
A must read if you’re fan but I’m not sure a casual reader will get as much enjoyment out of it.

A manga miniseries that explores the early lives of the five Gundam pilots, as well as the events that directly precede Operation Meteor. Written by Katsuyuki Sumisawa, the writer of the series, this is the most "official" of the Gundam Wing manga; it's still not great. Some of the backstories work, but they as often undermine or merely reiterate aspects of the show. Condensing angsty backstories into 30 pages makes them both rushed and heavyhanded. But the Operation Meteor chapter is fantastic, well-cut and less redundant, not as far reaching but filling in some interesting missing details.