Disclaimer: I didn't buy a D-X1 from this site, but I'll comment on the D-X1 battery that came with my BBy Bold 9650. In a nutshell, it doesn't last long enough anymore. It worked fine the first 3 or 4 months after I bought my phone, but now, it only takes a few long (avg. 20 minutes) phone calls, the phone working to find a signal (and I live in L.A., so we always have a signal), or a few Internet searches before the battery is drained to almost 0 power.

Looks like I'm going to have to buy a second battery...which is probably what the manufacturer wanted me to do in the first place.