This really isn't obvious at first glance; CV sticks very closely to the traditional gameplay style pioneered by the older entries, including the tank controls, fetch quests, and file reading. The level design is dominated by large mansions, labs, and a few outdoor areas, once again in keeping with earlier titles, though it was far more expansive than the previous three. Here's an initial issue: the level design is almost too expansive for it's own good. Like the original RE, you get an overhead floor plan of the areas you're in, but unlike the original RE, you're not limited to an extremely compact area, and quite frankly, none of the rooms are shaped oddly enough to provide landmarks of sorts. Every room is a different sized square. This does not translate into a useful map.
Along these same lines, each one of the rooms was just non-descript enough that I could never seem to remember what was in each one or where it led. To make matters worse, the sheer amount of them made them just blend together; there was never a point where I felt like I had a real idea of where I was going. The original RE technically "looked" all the same, but once again the fact that the area was so severely limited allowed the player to absorb where all the doors led. RE4 deals with its impressively expansive areas by making each one look different and providing an extremely helpful map (besides being exceedingly linear).
Naturally fetch quests were a cornerstone of the series, but CV took this to such a ridiculous extreme that the entire game felt like nothing but one gigantic fetch quest party with a few zombies tossed in to provide some kind of challenge (as if the level design didn't make it hard enough). The fetch quests and puzzles in the original RE were silly, yes, but they at the very least made a small amount of sense within the context; you had to find a book to place with other books to open stairs up, or use the clues on the wall to mix the exact right chemicals to kill the evil plant zombie. You were never at any point needlessly loaded down with too many fetch quests at once either. Code Veronica has you picking up emblems, plates, useless guns, insects made out of jewels, and various other pieces of junk at every turn. At the point I quit the game the first time I had a painting, two "proofs", a plate, and various other pieces of ridiculous brika-brack in my magic chest. To be honest, this was, in fact, the main reason I quit; I was faced with a pile of various junk that needed to be placed in their various respective holes in the game, and the thought of not only having to retraverse the areas to get it all there, make return trips because my carrying capacity was so low, all while painfully low on health with very little ammo to keep zombies at bay and no hope of finding any more health items...this was too much for me.
Just to be fair there are a few good elements; the main character is actually pretty cool (I don't care what anyone else says I like Claire), the combat knife is the most useful anyone ever gets in the entire franchise, and that chick can take an ungodly amount of damage. I mean, she's a fucking TANK. The plot, although it was pretty weak even for a Resident Evil game, still provided some extremely amusing elements (cross-dressing insane main villain) and some important plot points for later games (Wesker being all un-dead and self-elected main villain for the series from this point on). So I suppose in some ways it's not a total loss. It's just unfortunate that, if the level design and fetch quests had been more fine-tuned, the game really wouldn't be half bad.
To sum up, the terrible plot elements, characters, and voice-acting can all easily be forgiven if only the game itself is FUN. Code Veronica manages to make you feel like you're working, not playing an enjoyable video game. And this is its ultimate downfall. When your players quit the game in frustration then you've failed them in a huge way. Fortunately, after RE0 ended up being even worse than CV, Capcom got the message and now RE is (argueably) getting better with each new installment.