Where I live there are not many music shops dealing in ukes, and those that do have a rather limited range so I've had to resort to online shops. I've had nothing but positive experiences buying online fromm Hawaii Music Supply; not only are their vids and reviews extremely wide-ranging and thorough, they also pay great attention to customer service. It's better if you email or call them if you have a specific brand, sound or model in mind. They're always a great help.
Best part is they have a solid return option (which I've never had to use).
Best of luck!
I agree, HMS is SUPERB and I highly recommend an online purchase with them! Excellent customer service, HUGE selection of ukes, AWESOME set-ups, and they have a generous trial period (I believe 7 days in which to notify them if you aren't satisfied). And, yes, their videos are so helpful, too! I have had two ukulele purchase experiences with HMS and they were both extremely positive.
Additionally, I have also purchased 5 ukes online from private sellers (in these situations, there weren't any trial periods offered, but I was willing to take the risk and I didn't ask for a trial). Two of the five purchases ended up putting me kind of in a tough spot, but it was my fault for not asking enough questions before I made the purchases. I look at those purchases as part of my uke learning curve.
Finally, from my local music store, I purchased 3 ukes; being able to try the ukes on the spot was super nice. However, the selection of ukes wasn't as nearly as large as compared to many online retailers. The staff at my local music store also didn't seem to know much about the uke or the uke products they were selling, so that was somewhat of a impediment.
Also, to answer your question re: online reviews (sorry it has taken me so long to get to this): I definitely used online reviews on YouTube and other web resources (many reviews here on UU, actually) as a huge factor in my purchase decisions.
Hope this info is helpful.
Happy Strummings!