I just so happen to have both of the Archives games out right now. RE0 was great, and this one is exactly the same...exactly, except for on little thing, it seems that Capcom redid all of the text in the game, especially the typos in documents(one in particular that called William "Barkin", rather than Birkin). Otherwise it is really fun, in fact when I was playing just recently I unlocked the machingun for the first time.
I think it has to do with the difficulty, I got an A on normal...
Anyway, I recommend it, and it will keep you playing for awhile, since it is pretty much the most challenging game in the series, RE0 & Code Veronica anyway.
And, if you say you are fond of Billy, I think you should definately get it, since the Billy in UC was actually kind of lame, he didn't have his smooth criminal voice from RE0.