Some people like them and some people don't. Try some out and see which group you fall into. It's not hype, they offer a different ride for different riders.
Where you typically ride will have a lot of influence on what you like as well.
Notable upside of Plus: greater traction going uphill in steeper than average grades on looser or nastier trail tread. If you have intermediate level cornering skills, you'll appreciate the 'no-fail' feel of wider tires.
Notable downsides: They're fragile….way more so than well-built enduro tires and standard fat tires. Lot's of flats and sidewall rips…not sure why this is true, but do some research (either anecdotal or deductive) and you'll see that it is a common complaint. They climb slow, those that like to do piles of miles (especially hilly piles of miles) aren't going to like them, and they handle very differently than standard enduro tires or 29ers-some will prefer one over the other.
I have had the opportunity to ride a number of these bikes, including bikes that come as either plus or 29er in both configurations and I've preferred the New standard 29er to the plus bike in every case. Also, much of what I like about plus bikes, I think Fat bikes do better--so if you are already a Fat bike fan (or fat curious) make sure you check out the better Fat bikes vs. their plus-bike rivals.
Best plus bike I've ridder was a 29er Plus (Trek Stache 9..which is really a wonderful bike)-unfortunately the 29er plus is the one standard that is on the losing end and just hasn't caught on at all. So, I'd be leery of dropping real money in one of these. Too bad, it was the best one.