Great DIY just did the job today took about 2.5 - 3 Hrs
Just replaced my front pads and rotors today, no problems, just need a little muscle removing the caliper from the rotor and the 16mm or the 5/8" bolt that holds the caliper on.
Heres my take:
Front brake pad and rotor change on a E90 330Xi
I used this tutorial/DIY as a guide and its pretty simple job, i have an mechanical ability/and my job entails me working with my hands and using tools, so I felt very comfortable doing this job myself (I had a helping hand from my friend)
I used OEM pads, rotors and sensors.
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Caliper
The bolt that holds the caliper on, the 16mm for the front caliper, I found that a 5/8" held a little tighter so I used that instead of the 16mm. These bolts were really on there so I sprayed some Penetrating Oil on the top and bottom bolts to help get them off. Worked very well and came off alot easier.
It was tough to get the caliper off over the lip of the rotor so i used the end of my breaker bar to help pry and loosen it a bit from lip and then used the rubber mallet a bit till it was able to get it off by hand. But some muscle would due if you don't want to wack the caliper
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Pads
Removing the pads came right out, no issues
I had to bend the spring on the back of the back pad (one that goes in the piston w/ the 3 arms) a little bit to make it fit in the piston easier. Other side it slipped right in so no bending was necessary for the other side.
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Sensor
Was easy! You just yank the old one out, and follow the cable of the sensor to the little box, un-clipping the cable as you follow it to the box. Open the box and unplug it.
New sensor was a little difficult. First install the new pad, there's a groove for the sensor in the pad. Then plug the new sensor into the connection in the plastic box and follow the same way the old cable was clipped in, clipping the cable back in till you get up to the sensor part. Take the actual sensor and push it into the new pad were there is a groove for it this is were i took me a couple tries to get the sensor into the groove, it just wouldn't clip in. I let my friend give it a try and he tried numerous times till he used a flat head screw driver to help guide it in and he got it.
reset the sensor using this video...
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Rotor
Rotors were easy to take off and on. Undo the 6mm hex bolt, a little Penetrating Oil around the hub and a rubber mallet to wack the rotor a couple times at an 45 degree angle at the top of it. Came off and put the new OEM rotor on with not problems, screwed it back on with the 6mm hex bolt and good to go.
I used this DIY from Mr. 5 for the process, this is just my take on what i did and a little bit more explaining some steps.
Good Luck!