I use a general recreation GPS (Garmin 64) instead of a cycling specific model because I also use GPS for backpacking, canoeing, hiking, etc.

If I have a route in the GPS that I have laid out at home on my computer, I get beeps before I should take a turn. Not verbal directions, just beeps. That is good enough for me because it warns me to look at the map. I think it is two beeps, one a good distance away for warning and one close by. If I am in heavy traffic with a lot of noise like in a community at rush hour, I might not hear it but otherwise I hear it.

Also when I tell it to take me to a specific point, it calculates the route and beeps every time I should take a turn. If I miss the turn, it recalculates and tells me later when to turn. This can be a bit of a hassle, last summer on a bike tour I decided to follow a bike trail for most of the day but it kept trying to re-route me to roads. So, every road intersection with the trail it would give me a couple beeps because it was telling me to leave the trail.

If I am following a track, I get no beeps. The track is shown on the map in a heavy purple line, thus I need to look at the map occasionally to make sure I do not miss a turn. For example, when I use it for riding a brevet, I put the track into my GPS and follow the track, a couple times I glanced down and found I was off the track, so I had to turn around and go back a few hundred yards to get back on track.

I have occasionally taken a wrong turn with the beeps because of heavy traffic prevents me from looking at the map or complicated road like an odd shaped round-about in traffic, but I consider those rare experiences to be user error.

My automotive GPS gives me voice, but that device is not waterproof and the internal battery only lasts a few minutes.

I have never owned a cycling specific GPS so I can't comment on those.