I own this and also managed to get my hands on the other Live arcade disc that comes bundled with the Xbox Arcade console package i.e Pacman CE, Feeding Frenzy, Boom Boom Rocket.
It goes without saying that Unplugged is a fun collection of games Geometry Wars being the standout title with the rest ablely supporting with varying degrees of addictiveness and fun-hair pullingly frustrating achievements.
Whats also apparent though is that the Live experience has moved on quality wise. There are games like Sensible World of Soccer, Castlevania, the aforementioned Pacman CE which is super addictive, N+ a great remake of a flash based PC freeware game, and the classic Dreamcast title Rez which quality wise eclipse the titles included in this package. Even though this collection represents good value there are cheaper ways to get your hands on some older retro goodness for your Xbox - Capcom Classics, Midway Arcade and Taito Legends for example offer much more in the way of games per package, a nice frontend and are genuinely retro. They also offer concept art and the backstory to some of the games.
Unplugged is a good collection but Microsoft should take note that there not really showcasing the Live Arcade experience of today with this collection of games and get another Volume out there mixing up genuine retro arcade, remakes and original titles plus get some XNA developed stuff on there.