I bought this unit a little over a year ago and have used it on no less than a dozen lengthy road trips since, as well as countless shorter trip around the city I live, and it has always gotten me to where I want to go.
When you power the unit on for the first time, you're given a grace period of I believe 60 days if my memory serves me correctly to go on Garmin's website for a free map update.
This unit has a lot of bells and whistles and I can tell you right now that most of them are useless. FM Transmitter: I tried this one time and immediately changed it back to the default setting. First, it doesn't sound any better or clearer than the sound coming through the unit itself, and to make it worse, you can't listen to your radio when this feature is in use. Instead all you hear is static and radio frequency waves.
Junction View: These features are all marketing fluff. Don't fall for that fancy graphic that they display to sell this unit. I live in Chicago and this is the only place where I've ever seen Junction View show up. I've taken trips to Detroit, Indianapolis, Louisville, Cleveland, Milwaukee, Grand Rapids, and Iowa and I don't think I've ever seen it show up in any of those places. And even if it did show up, I can tell you that it has no real effect on your ability to make the right decision on where to go. If anything, it's a distraction since it takes away your map view for a few seconds.
Lane Assist: I've heard some people say this is useful to them, but to me it's the same as Junction View. Is knowing that there's a double left hand turn lane ahead really going to help you in most cases? For me the answer is no.
Mp3 player: complete waste of time. I thought maybe the music would feed into the car speakers, but no. It plays through that tiny itty bitty speaker on the back of the unit and sounds like complete garbage. What can you expect from a speaker that's 1 inch big!
However there is one feature on this unit that I absolutely love, and that's the speed limit sign that displays in the bottom left corner next to the speed that you're actually driving. This is really useful because when you're traveling on unfamiliar roads, it's a given that you're not going to know what the Speed limit is. I've found the feature to be at least 90-95% accurate, right down the very spot on the road where the limit changes. But there have been occasional times where it has been off by 10mph, so it's still wise to pay attention to signs every so often. And as your map becomes out of date, I'd expect the accuracy to go down as well.
The biggest glitch with this unit is the touch screen. The calibration is off and it leads to you often times entering the wrong selection. It is a bit annoying, but for me this is something I can live with because I rarely enter new addresses into the unit and in general, I only use a GPS for the occasional road trip.
But if you're someone that expects to use a GPS on a regular basis, like for work or whatever, then I'd highly advise going with a different unit because the problem will drive you up the wall.
EDIT - Review update (July 30, 2011): Garmin has recently released a software update (not to be confused with map update) for this unit. After the update the touch screen problems have been noticeably improved, although still not quite perfect.
Another new feature in the update is your driving speed will change to the color red when you exceed the speed limit. I do not like this new feature because first off, who actually drives under or exactly at the speed limit? Nearly everyone does at least 5 mph over around here, which means it's almost always showing in red. Secondly, the red text is harder to see against the white background, or navy blue background at night. /end edit.
Traffic feature: I don't have too much experience with this. I've only tried it twice, but it seems fairly accurate. Perhaps not as much as one of the pay plans, but for free I can't complain.
And most importantly, you're wondering about the directions? After all, that's the primary reason to buy a GPS. Of all the trips I've taken, it has always taken me from Point A to point B with ease. There have only been two occasions where I disagreed with the directions it gave me. Both times it wanted me to get off the expressway and take side roads to another nearby expressway. I ignored the directions and let the unit recalculate so it took me from expressway to the next expressway. All other times, the directions have been flawless. Recalculations are about as quick as you can expect, and I've never had the unit lose the satellite connection.
Overall, aside from it's few problems, it is a nice unit. Knowing what I know now about the bells and whistles being mostly useless, if I had to do it over again, I would maybe look for a more basic unit, as long as it still had the speed limit feature.