As I haven't played NFL GameDay 2000 or any prior version of GameDay, I cannot honestly compare it to previous efforts. What I can do is agree with everything else Ben has to say about the game, but I'll try to be brief to avoid parroting his every word. The two major points of the game that I have the most problems with are the graphics and gameplay. As you can plainly see from the screenshots available, GameDay's visuals are so plain they might not even look impressive a year ago. The character models are standard and the colors look dingy from almost every angle. When compared to titles on the next-generation consoles, GameDay 2001 begins to look even worse.
As far as the gameplay is concerned, it seems to be made solely for fans of the original. I say this because I can't see anyone implementing such an archaic control scheme this late in a game's life, expecting gamers to adapt to it. Once on the field and the ball was snapped, it was ridiculously difficult to complete routine passes or gain even a modicum of yardage on hand-off plays. The complex controls certainly just got in the way at times—football games publishers should include a disclaimer advising ample hand stretching before playing to avoid injuries from to the arduous finger gymnastics I was required to perform.
Something as relatively simple as getting my receivers up field was a chore. With the unrealistic pacing Ben mentioned, it could prove be quite daunting. It's evident in every part of the game. From the time the ball touches the hands of the quarterback—there never seems to be any time to hit a receiver or select a new one—to when it's fourth and goal, there seems to be defenders flying at you before you really have time to react. Also, as Ben mentioned, it is easy to lose sight of the receivers and defenders because their character models break down as they go off into the distance. What winds up happening is that they become pixelated blotches that run into and away from each other with little to really distinguish them.
When all is said and done, NFL GameDay 2001's weak graphics can be ignored, but the flawed gameplay cannot. If there were ever a reason to release a sequel, it would be to correct these crucial problems, but 989 Studios and Red Zone Interactive evidently saw no need to. Since they saw no need to improve their own game, I see no need to give it a decent rating.