I think people are too quick to dismiss the use of radar in local areas, at short range. Generally I hear them saying radar is only needed on the open seas. The first time I ever used mine on my old Albin trawler it warmed me of an idiot coming up behind me at a high rate of speed. It will allow you to monitor the area around you and is especially useful when coupled with the proxicimity alert allowing you to track specific targets. The fellow who bought the Albin was caught on the Tenn-Tom (the waterway between the TN River and Mobile Bay, AL) in heavy fog approaching dark. The big tug boats with their tows were still running the waterway which is a very small place with those tows around. He swore to me the radar was the only thing that allowed him to get to shelter.
The main problem with radar is the cost, not just for the set itself; one has to have a device to display data. I like to overlay the radar picture on the chartplotter display. That's not inexpensive. Neither is radar with its own display unit. Even buying discounted Garmin equipment I spent about $4,000 dollars, that's with me doing the installation.
I'm a Garmin fan. I currently own three units, did have four. One is a simple device which gives a rough picture of your surroundings, shows your location on the picture, allows you to track a person overboard,(if you hit the button), allows you to go to a preselected point, shows deviation from course, gives speed, time of day, tide tables, lat. and long.(position in degrees, minutes, seconds), gives a track of where you've been, along with a host of other data. Simple?
The other units provide more info in more detail. One has a depth sounder. My R-21 EC came with a Garmin 545 S unit. The "S" is for sounder. It's a very nice unit, however it didn't come with detailed data covering my area. That was $100 to buy that piece of software. I also dislike the display of land area, it's accurate enough, but is fuzzy and occasionally switches colors to yellow and then goes fuzzy again. It doesn't accept radar overlay and I'm getting the impression it won't "talk" to my VHF, different languages.
On the Albin I used the simple, basic unit to plot courses on the paper charts I had on board, in addition to the complex system. Worked great. Two units are nice, as is navigating with paper charts. If one system fails the other one keeps you safe.