I use eos remote on galaxy note 3 to shoot landscapes, fireworks, family portraits, and difficult-angle shots with my 6d. It drops the connection sometimes, but it usually picks right back up also. I have yet to have one bit of camera equipment, computer, software, phone - any bit of tech that does everything it's supposed to do all the time or is otherwise flawless. While I find the 6d wifi and canon software adequate for my needs, I would still buy a 7d II, depending on the price, whether it has wifi or not - I'd just rather it did...
Same experience here with my 6D Wifi. Useful and generally workable. However, I suspect the 7DmII target audience interested in remote capabilities might be better served by a CamRanger or equivalent rather than 6D/70D-type Wifi and EOS Remote app. Features like an intervalometer, discrete focus stepping, motorized tripod head interface and much richer set of camera controls would be more appealing in the field (e.g. shooting star trails from the comfort of your tent, or bears from a safe distance).
Looking forward to seeing the details on this beast. I've held onto a 50D for shorebirds even after going FF, so a better performing APS-C might lure me back for my wildlife work.