It was an innovative package -- minimalistic, extremely compact, not using a full standard USB A-type connector, but compatible enough to be able to plug into a standard A-type slot. A significant drawback is that the very small size makes it very easy to misplace. A holder is offered to make it the size of a standard USB flash drive.
The faster "170X" version offered unusually high claimed speeds of about 25 MB/s, at the time of introduction in about 2004. (The X1 reference speed is the original CD data rate of 150 kB/s.) By 2006, USB flash drives are commonly available with claimed speeds of 10-25 MB/s. Nevertheless, typical overall data throughput speeds on ordinary computers are often only about 3-10 MB/s in actual use, due to a variety of factors.