Definitely worth a purchase for fans of this type of game, or RE nuts. The game itself is pretty challenging in later stages, and the pace improves a lot once you're through the first set of missions. It's deeper than I expected, and the ranking and weapon improvement is a great incentive to keep playing missions over and over.
That said, it's painfully obvious that this was a pretty low-budget exercise - reused assets from earlier games, little new content, reused files in the document archives, the RE3 scenario which completely butchers the original so it can use Outbreak environments etc. - and while it is attractive in sections - mostly the mansion, IMO, with the Neptune tank being a good example - it is not up to what the system is capable of.
I'm having a blast with it, and I can accept its faults because I'm aware of its development history, but if Capcom are going to bring any more RE titles to the system - and I sincerely hope they do - they should now be looking at actually putting more talent and money behind them and coming up with something a little fresher.