This beer has a powerful corn nose and flavor and a nice straw-like maltiness balanced by a deep hop bitterness. The corn is not something you would expect from the style, but if you imagine it as a pre-prohibition American Lager, it fits the bill: A heavy, heady nose, laden with corn notes but not a lot of hops; It's orange-hued and somewhat cloudy, with a nice, rich, effervescent head. It starts sweet and grainy, but resolves into a deep resinous bitterness that lingers on the tongue. The overall effect is nice, but it would be hard to drink two.
Edit: I feel like this review needs some commentary. This beer was submitted as a Czech pilsener, which is a crisp, malty, hoppy, clean continental pilsener. The actual classification is "bohemian pilsener" and Pilsner Urquell is the benchmark for the style. Morimoto Imperial Pilsner clearly did not fit the style, being quite a bit bigger, hopper, and just all-around boozier beer than a crisp, easy bohemian pilsener would be. In addition, there is a strong corn flavor, which in European pilseners is considered a defect.
The corn is from DMS, di-methyl sulfide, a naturally occurring result of the brewing process which is often found in American pilsner styles (think Rolling Rock). It was probably quite common in Pre-Prohibition lagers, as the early American brewers did not have access to the same technologies as their European counterparts. I decided to review the beer as such.
The American Classic Pilsner (A Brewer's Association classification) is the latest iteration of the Pre-Prohibition lager style. It's a catch-all for pale lagers that don't fit the modern American or European lagers, and a really good fit for Rogue's imperial pilsner. Early American settlers from europe brought their beer-making traditions with them as they settled across the United States, and the style is meant to recognize the lagers our early brewers probably made, with what they had available here. The Rogue Morimoto Imperial Pilsner itself is big and boisterous, not at all delicate, and I can imagine it being one of the more popular beers 100 years ago. Corn character is totally appropriate for this style as well. As a Classic American Pilsner it fits the bill, and I stand by my review.