I bought this GPS because it does what my girlfriend's doesn't, play music from the SD card while navigating. This was something I required due to not being able to hear the GPS over the radio. So, I just plug the head phone jack into my car stereo to reroute the sound. While it works I have been unable to get the play list to work even after extended e-mails with tech support. This is a major issue for me as it makes listening to things like audio books impossible. If all you want is a music shuffle this issue will not affect you.

I also live in Michigan where we have a unique road feature we call the Michigan left, this is, as far as I know, unique to Michigan. In order to turn left you either go past and make a U-Turn on a small connecting street or go right and do the same, no turns at the actual intersection. The GPS-510 seems to be hit and miss when you need to do a Michigan left. The problem is that normally this is on two or more lane roads and being in the wrong lane is a big issue as you can't make a left and need to make a right.

The girlfriend's Magellan GPS is more granular for directions, if there is a possibility of you going the wrong way it will tell you where you need to be, to include navigating a clover leaf interchange. This GPS believes that once you are on the right road you will stay there until it tells you otherwise.

I have found with both GPS units that for local trips you probably know a better way to go, either due to traffic flow or light timings.

I bought two GPS from amazon one for myself and one for my friend. After opening package i followed the process suggested by Harmon Kardon to start the GPS for the first time. First GPS froze while initial setup only. Even after several resets it never completed initial setup. Second unit was also facing problems in initial setup but it completed initial setup after several resets. I used that GPS for a testing it lead to wrong destination. It asked me turn on dead end streets. I could never access its music and video functions. Then I tried to call HK for its firmware update but they asked me to return device to reseller.

Picked this up on a Gold Box deal for $200.

My wife was especially interested in the MP3 capabilities, but unless you happen to have a stereo with RCA input jacks, the only way you can listen to the songs you put on it would be using the little speaker on the GPS. (I guess if you have a mini-jack plug in, you might be able to convert the two RCA's to mini-jack and plug it in that way.) But if you have neither of these options, it might just be better to get a new stereo.

Okay, what about the GPS capability? I'd give it a 95% thumbs up. A few times it screwed up where it would "merge in the left lane, now prepare to turn right"??? Also, we took it on a trip to a concert in Manchester, TN. We stopped in Brentwood, TN for our hotel, and it took us to xxxx Lane instead of xxxx Street, and we had to stop and ask for directions.

On the positive side, it's great to have in a city where you have no idea where you're going, and don't have to stop a look at a map to figure out where you're going.

There's plenty of restaurants, stores, tourist site, etc. programmed into the unit too. Just type in an address, location, whatever, and you're ready to go. Plus, there's a battery so you can do all of this in your hotel room.

Something I would like to see on it is a better way to look at maps to plan a trip, and a way to say to it, "Hwy X is backed up, find a way around it"

For the price I paid, it's great, and the feeling of confidence it gives you driving around an unfamiliar city is well worth the money.

great item. Just used it through Calif., Oregon, Washington and B.C. Canada and didn't get lost once. Great time saver and easy to use

I bought the GPS on impulse as someone who has gotten lost in unsavory places. One day I had to get to a meeting , had no time to map quest. I ran out the door, entered the address and followed the voice the whole way, and it got me there easily. My only complaint is that is doesn't activate until we are in the street. But it estimates time involved in the travels and adjusts the time as it calculates the real time speed. Having a 17 year old driving it gives us both a level of comfort that he can get places easily. Great!

The GPS has worked in most occasions. The address entry is intuitive and easy to setup. I have seen the GPS not identify some fairly new locations , however. This has only happened once so I am giving the benefit of doubt to the product. With Garmin, you have the ability to update the GPS software. I will be investigating to see if the GPS maps can be updated with this unit as well. The other Media player capability though is nice. However, I rarely use that feature in the car. The unit comes with a protection for the GPS unit when not in use. That is very helpful if you take the unit of the car and store it in the car.

Nice looking device, fits perfectly in hand. Touch screen is slick and very responsive... menus are easy to navigate and a home key is always present to take you back to beginning.

Charged it up and took it outside... was surprised when it locked on the instant i powered up... it had our spot on the map where it should be, so we started walking to end of street and the 510 tracked almost instantly when we were walking, as well as when we turned direction and headed back other way. Spent the next few days having it on in car and GPS function worked extremely well... never had any mistakes or weird routes (keep in mind only tested over a few days)... said names of streets clearly. Seemed to perform very well as GPS device.

Now for media player review:

OK, first of all -- the screen on it is very sharp and crisp... demo movies, and movies i loaded on to it, display very nicely. converted some dvd's to .avi or .xvid (cant remember which right now) and it played with no problems.

Anyway the biggest disappointment in the media department is that there are virtually no basic options/controls for mp3 or video playback. On videos there is absolutely no options to select from (zoom, full, etc.)... but they played well, so not a big deal.

MP3, however, is a different story. There is no "now playing" feature, nor the ability to create playlists from the player. (and of course no equalizer options or anything else.) So say you have a bunch of pop songs on the player and a bunch of classical and/or comedy tracks -- if you are in your car and you want it to shuffle through all of your pop songs there is no way to do that unless you have made a playlist on your pc comprised of only pop songs and have downloaded that playlist to the player. VERY restrictive. You can sort by artist/track/album in the player.... but you can't choose it to select more than one specific artist/track/album at a time. So if you want to listen on shuffle -- it's either shuffle through EVERY song on the player, or shuffle through one artists tracks. you can't specify more than one of any category to play through the player. Big bummer.

Add into all of that the fact that you are restricted to a max of 4GB of storage on an SD card -- so a couple of movies and you are going to have to buy another card if you want to carry around a lot of songs at the same time. Oh and no ability to view pictures either in case you wondered.

Summary: If you are looking at this as the perfect device to include mp3,video, gps -- i would pass. Personally the restrictions of the audio playback, along with no pics and 4 gb max just wouldn't cut it for me. I use my mp3 player (creative vision w) all the time in car, in house, etc. and need those basic mp3 controls. The extra price of the 510 for the media capabilities isn't justified IMO. For the same price of the unit ($400ish) i can get a nice gps only device and a solid media player (creative w for instance) with 30 - 60 gb of onboard storage.

Now if you aren't a big mp3/video user, then perhaps you would be satisfied with the limited media options as a trade off for the convenience of having it all in one package instead of having to carry around 2 units.

Hope this helps someone.