Originally Posted by Ryuukishi
Mostly a collector/completionist thing.
Some of the preorder bonus items are interesting but they're not radically different from what's in the base game. Now some of the paid DLC guns that were introduced later do outclass the regular stuff (Locust, Mattock, Kestrel armor).
Out of the pre-order items, I think the only thing I actually used was the Blackstorm. Initially, I may have used the Terminus armor and the Inferno armor for ME2, though by the time you make it through a few levels and buy some upgrades, the basic armor + upgrades works best.
The Mattock is the best paid gun you can get, IMO, with the Locust right behind it. The Arc Projector was the best free gun you ended up with, IMO.