Probably. Any forum you read you'll find haters of one brand or another. There are many reasons IMO.
Some people just shouldn't be near electronics and technical gadgets. Doesn't seem to be related to their educational background or intelligence.
Sometimes it's a particular and obscure feature that many don't use or care about, but does matter to those that complain.
Sometimes you just get a lemon.
Sometimes expectations of what the feature is supposed to do isn't what it really does.
Sometimes a minor misunderstanding of how to use a feature causing you to think it doesn't work.
Lot more reasons too.
But as for Turn-by-turn navigation. There are so many things from brief interuptions of signal reception that you won't even know happened, different ways turn cues are generated either by the devices software looking at the actual map file or simply reading the course file, or how different course generating software sets up those cues that to me it's a miracle that it's useful to anyone at all. It's not as simple as your Nuvi or other gps for your car.