Looking At A 2004-6 S-500 4 Matic
 

These any good or am I looking at something that I'll will regret

The newer the model the better. THAT is true 99% of the time on any car line.

The W220 chassis has(had) several shortcomings, almost all were addressed during the production run.

If you've found a nice, MB Certified Pre-Owned car then go for it. If it's on a used car lot, or it's some other kind of "great deal", you could be in for trouble. A nice W220 is a nice car. A "not nice" W220, regardless of the price, could become a nightmare.