It all depends on how you are using them and exactly what they are overwriting.
If you are creating a module to share with others, then you really should just use haks. Many popular overrides exist in a hak form already and if they don't, its fairly easy to turn them into haks.
If your desire is to enhance things in a stand alone module, including the OCs, then overrides for most creatures and tilesets should be fine. If however you also play on PWs, overrides may or may not be a good thing. While some appearance changes might make most of the game seem better, often it can skew what the original builders designed around and actually detract from the "feel". Overrides that expand on feats, domains, skills, classes and other mechanics can also cause glitches when you create characters. Using an override for "heads" could have you creating a PC on a PW and choosing a head during PC creation that once IG others either cannot see or see a different version. Most PWs have extensive character customization available after you enter anyhow and a lot of the older head, hands and feet, and other overrides are redundant anyhow.
It really all depends on whether you are playing on a PW or just playing solo modules.
