I just came out of an M5. This X5M is better. It handles shockingly well despite being an SUV. It telegraphs its limits better than the M5. The interior is superb. The iDrive and Bang and Olufsen stereo are wonderful. BMW has done a great job in moving the iDrive platform forward. The level of voice control over various functions has improved considerably over my '14 M5. Fit and finish have been excellent and no complaints. When you combine the performance and technology of this vehicle with the quotidian practicality of how much it can haul you will really want to consider it if in the market for a 5-series/E-class/S6-7 Audi.
This vehicle is excellent mechanically and performance wise, aside from averaging about 10 mpg. However there are other critical drawbacks. My major complaint was the quality of the paint on the vehicle. It had noticeable splotches along the front roofline, rear hatch and gas cap lid that became apparent when viewed in direct sunlight. Three different paint experts said this was a systemic problem with the paint application at the manufacturing plant. The dealership replaced the gas cap lid but refused to address the other issues. Their reasoning was that those same splotches were evident on other X5M's. The manufacturer sent a technician out and he said he couldn't see them. Their customer service is the worst I have ever dealt with. We dumped the vehicle and will never buy another BMW.