The watch, the first new product to be launched by Apple under Chief Executive Tim Cook, will hit stores on April 24.
Most reviews, while praising the watch's sleek design, highlighted its relatively short battery life - up to 18 hours, according to Apple.
The fact that it relies on an iPhone being in the close proximity for most of its functions to work was also seen by some reviewers as a drawback.
Paired with an iPhone, the watch allows users to check email, listen to music and make phone calls. Apps will also allow users to track their health - for instance by tracking heartbeats and the number of steps a person takes.
The battery was often nearly drained by the end of the day, especially if used during exercise, while Scott Stein said recharge time was slow.
Re/Code's Lauren Goode said that while the watch's battery life was not nearly as long-lasting as some other wearable devices, it was better than she had expected.
Apple is among several large tech companies hoping to jumpstart a new market for wearable electronic devices.
Samsung Electronics Co Ltd, Sony Corp and LG Electronics Inc have all released smartwatches, many of them powered by software developed by Google Inc.
The Apple Watch Sport will start at USD 349 for the smaller, 38-mm model. The standard version will start at USD 549 and the high-end "Edition" watch will be priced from USD 10,000.