Options do not a real BMW make. In fact, for me, it's more important to have fewer options than more. My 323Ci is lightly optioned not because money was a factor (it really wasn't) but because that's the way I prefer it. With the sport package, heated seats, a CD player, the high-end audio, and a sunroof, it has everything I need. I want a sports sedan (coupe), not a rolling bordello.
Things like rain-sensing windshield wipers, wood trim, leather interior, etc. all have negative value, IMO. They add weight, complexity or maintenance costs and offer no real benefit. So why should I a) pay more for them, or b) care that my car doesn't have them, while some other similarly priced car does? In this sense, I really like BMW's a la carte option system. It allows me to tailor the car exactly the way that I want it, rather than having to accept a bunch of crap to get the good stuff.
As for performance, it's hard to compare the IS and the 323. As I said, the IS was not available with a standard transmission when I was buying, so its horsepower level was completely irrelevant to me. No stick, no sale.
As against a 325, it's difficult to say how the manual transmission IS will fare. No 3rd party performance numbers have been released. However, IIRC the Autoweek review guesstimated 0-60 times in the high sixes or low sevens. Those times are much closer to 325 territory than to 330 numbers.
Regardless, I don't really care whether my car is faster or slower than car X. Speed is one part of the equation, but if all I wanted was a fast car, I would have bought a Cobra. FWIW, the Cobra has more than 100 hp more than the IS, and costs less.