Yes, I have some good experience with them in my line of work. Here is some of the lowdown that I tell everyone.
Not all recorders are the same, your #1 key critical aspect is PLAYBACK and SEARCH. When you need to pull up an event in the past you do not need to be fiddling with the search feature nor spend much brain power in figuring out how it works. Those situations you are stressed out and you will not be thinking clearly, so any thing overly complex in usage should be a red flag of what not to buy.
Things you should look for is the search/playback software that shows a time based graph based on motion activity PER CHANNEL. That way you can quickly look at camera 1 and say oh! at 2:37am there was some activity, lets see what that was. To many search features are scaled down where you must enter the camera and the start/stop time frame then play it back at normal/double/triple speed until you find the real event time. Honestly no one has time to do that when you will be needed that playback footage.
Second thing is all to many times people like to show the monitoring stations to 'help reduce crime' as they put it. What really happens is you show the viewing locations and where you need to be to avoid the cameras. In short, put that crap up and out of viewing reach. In fact put it in a safe where it would not be stolen in a break in (yes I have had several clients with cameras have the dvr stolen because they were out in the open and was the 'hey we have cameras!' slap in the face.)
Remote view is one of the strongest features you can employ. I have some offices that are now in less savory locations in the area so they use the remote feature of the camera to see what is going on before they get there. Showing this info on the iphone, ipad, remote PC, tablet etc. should also be looked at.
Cameras can be a very bad thing if used improperly (i.e. red light cameras) or a very good think if used properly.
I had one client with a camera at home, it picked up a car driving up and down the street, backed into their driveway then turned around. License plate was on camera and very clear to read. One guy got out, face very clearly defined, kicked in the front door and took every electronic item they had, jewelry and 2 firearms. Video was given to the police, they ran the plates and went to make an arrest. Instead of arresting 2 people they arrested 12. Inside the house they found it had 1,000 stolen TV sets and there was another 2 suspected houses with loot just as equal which they were selling to anyone. The police had no clue this ring was operating and not a bad deal for $600.
Had another client (doctors office) that was having problems with a cleaning company. The cameras were consulted and they discovered the cleaning crew would come in clean the bathroom first then use the same towel to clean every exam room table where patients were.
As for which unit(s) are good there are a number of them. Those with the best playback that I mentioned earlier include companies like Q-see. The better cameras today can show facial features 300 yards away in darkness.
