The OTR Vehicle antenna is great.
Been using the WeBoost vehicle cell booster with the 12" mag mount antenna over two years in Colorado. The 12" antenna works better than the low profile antenna that comes with the standard booster kit. About a month ago I purchased an OTR antenna in anticipation of a road trip covering Interstate, and US Routes through Colorado, Utah, Arizona and New Mexico.
While I thought the mag mount was a great antenna, the OTR provides another one to two bars better! We had no trouble with cell and data almost the entire time. There was probably 15 minutes cumulative over the whole trip where we lost Verizon or roaming service. The thing just hung on to each cell tower and grabbed the next one immediately. Most of the time we had at least 75% or more of max signal bars.
Of course, credit goes to the provider for their part, but in remote areas it was easy to see there would have been no service without the booster and antenna combination.
Had a little project improvising mounting for my pickup truck so the antenna head poked above the roof, but cleared the garage door without hitting it. You also have to justify the antenna's cost. In my case, it was certainly worth it.