Fallout 3 - Mothership Zeta Review @ GameZone

Linear, repetitive and some tedium still gets you a 7/10, apparently.  From GameZone's review of Mothership Zeta:

On the whole, it seems Mothership Zeta is a simple bit of entertainment that doesn’t last very long. Even if you don’t mind that it plays like a big shooting gallery, things tend to get rather tedious early on. There’s nothing that will keep die-hard fans from going nuts over it, but even they will be forced to admit that this is far from the highlight of Fallout 3. There are trinkets that can be collected, and much scenery to be admired, but not really enough to keep players coming back for more. When push comes to shove, the penny-pinchers will find the earlier downloads to be more worth the price of admission.