$299 is hefty. Like a PP mentioned, this would be good for someone with only one or two days at WDW (like a post-cruise) but wants to see a lot of it. Originally, I thought this might be beneficial for those who don't want to deal with the rope drop rush and waking up early, but looking at the start time (8:15am), that is clearly not the case. If you're going to be waking up that early, you can hit some of the headliners at MK in first two hours of park operation (7DMT, then Space, Splash, BTMRR, and HM is completely doable), then head over to DHS with FP+s for TSM!, Star Tours, and ToT and use the single rider at RnR. Finally, head over to DAK to get FP+ for EE, have a late-ish lunch, ride Dinosaur, and then use your EE FP+ (or you could just do single rider). The same thing for free basically though you may be waiting a bit more but not a huge amount.
What I wonder about is the admission situation. On The DIS's page, it says "park admission required" (which I wouldn't expect for $299), but how would that even work? Would guests need to have just a one-day MK ticket or need a Park Hopper?
To be honest, I've never done these VIP tours though I was listening to a podcast recently (recorded before these announcements by the way) that suggested dividing up the cost of the private VIP tours as the tours are for groups of ten.
So, in theory, three or four families/couples/friends could do something like this. Get to the park around 10am or so and have a big late breakfast in the park (so you can skip lunch", around noon, meet up with the VIP tour guide for six hours (min. allowed), then use FP+s for 3 rides you want to re-ride after 6pm. Finally, have dinner, see the nighttime entertainment, and take advantage of lower waits after that if the park's still open.
Considering the price of one tour is $315 per hour for resort guests in non-peak times for a minimum of six hours, that's a total of $1,890 for six hours (2,250 during peak), which averages to $189 (or $225 during peak) per person, which is actually cheaper than these new offerings. Still not pocket change by any standard but may be worth it if we (a family of four) go with two friend families (both of which are families of three) during Xmas/NYE. Unlikely, but still haven't decided as I'd have to start saving now!