This 525i is great. I never did drive the 530 so I don't know what I'm missing in power, but I traded in my 2001 Acura CL type S and do not mind that I gave up over 70HP and other cool features such as Xenon headlights, homelink, Nav, and a CD changer. My 525i 5 speed is a blast to drive and feels very fancy inside and out even without almost all the options.
In addition to the view from the front, I enjoy the seats, sound system, ac in the rear, and head lights.
I'm pretty sure the improvements such as more storage has already been seen in the 2004 525i