Just one week after Google launched the Nexus One, its entry into the smartphone field, the numbers are in and it doesn't look to be keeping up with the competition. We reviewed the iPhone-competitor the other day and see it as a formidable challenger, but sales numbers from its first week fall drastically short of those same numbers for other smartphones during their first week, according to statistics from mobile analytics firm Flurry.

While Flurry's own analysis of the numbers makes sure to point out that the statistics may not provide an "apples to apples" comparison, the Nexus One's first week sales were a fraction of its top three competitors.

Flurry details the methods used to arrive at these numbers in its blog post and is certain to call the data an estimate. But if they are even close to correct, the Droid, myTouch 3G and iPhone 3GS outsold the Nexus One by a factor, respectively, of 12, three and 80.

Whether it was Google's lack of marketing, the fact that the phone was only available for purchase online, or its $500-plus sticker price without a service contract, Flurry identifies a number of reasons for the slow start. The company also points to the post-holiday release date and the fact that Google did little compared to Verizon's $100 million marketing of the Droid.

We see a few other points that could have contributed to the slow start. For those using AT&T, the Nexus One works in slower EDGE mode, not 3G. And for the contract weary, news about Google charging additional early termination fees certainly holds some scare factor.

We'll have to keep an eye on these numbers as time goes on, but we're curious - what, if anything, has kept you from taking the leap?