I agree. I don't know what would prompt saying it is horrible.
I have the 7710. Same unit but smaller screen. I have used it on several trips with out any major problems. I have had lock up issues a couple of times which isn't good.
But it is functional. I don't know what it can't be as good as my car Garmin GPS. But even the Garmin units for use in trucks get bad reviews. There just seems to be some issues getting all the bells and whistle we want in the RV GPS to work all the time. I think just a lot of moving parts in the software. Hopefully they will work them out. Rand is always making improvements for download.
I am going to purchase the Rand McNally App for IPAD. It is $99 and is the same software as in the stand alone unit. I will use the difference in cost of purchasing the stand alone to buy my IPAD which I can use for many other purposes on the road and it has a 9 1/2" screen instead of 7" that is on the unit.