Hi Spill,
I have one Imperial, a hawksbill, and it's an ok knife. I don't use it very much, it did it's job and just kinda lays in a drawer now. I think the Imperials are made in Ireland, and are the economy line for Imperial Schrade.
As far as how they compare with the rest of the Schrade line, I think you'll find the quality much better in the Old Timer and Uncle-Henry lines. Better steel, assembly, fit and finish, ect. That being said, the Imperial/Apex line has styles that aren't available in the other lines, like the electricians knife, and the hawksbill pattern. For someone on a budget, they would be an acceptable choice, but I encourage you to try out the Old-Timers or Uncle Henrys. They aren't very expensive, either, and are a great value. You won't be disapointed. I have many brands of knife, but my favourite is probably my Old Timer 8-OT.