I got one last season...my first one also . They work well but it takes a little testing. It also complicates fishing slightly. For those that like to keep it simple...this is not for them. The reason you don't see a lot of them is that around here, the fish tend to hang around structure (rocks) and drop-offs. Trolling across or near one with most downriggers means an expensive hang.
I always avoided them until I read about one that has its own depth transducer and can contour the bottom. (you set it for a depth off the bottom and it adjusts auto-magically.) I tested it out and it is kewl and does indeed work. I plan to use it more this season when I troll.
Why use a downrigger...simple, cause wire plain sucks to fish with. I own wire 4 rods and 6 wire reels and have trolled them for my entire life from Fire Island Inlet to Nantucket. IMO while wire IS productive (no doubt about that!)...it is a lot LESS fun to fish with. Yes it is still exciting to see a big fish boated but the battle is unsportsmanlike and is the reason why the IGFA disallowed it.
When you use braid on a downrigger on a light rod...that is fun and a lot more comfortable.
All the charter guys troll wire...why? simple, it produces fish for brainless fisherman. You end up draggin the poor fish at at 3 knots and winchin him in....there is little sport, but you do put fish in the box. It is also hard work and there can even be painful at times.

Tube and worming on wire is like casting a bucktail...there is an art to it and it takes some experience to develop the technique. I don't hold it against anyone and I still carry the wire on board for slow days...but I like the rigger too.
No matter which model you have, it will take some time to get use to it. One nice thing about it is that you KNOW exactly where the lure is. You can put a floating plug at 58' if you want. Wire is a guessing game but I found the best way to fish wire is to keep it bouncing on the bottom from time to time so yo know your close.
Start off buy fishing a spot with near constant water depth with it until you get use to the features.
There is a guy here on this board (forgot who) who trolls live eels with downriggers and is very effective. I think I may try it this year...live bait on a down rigger.
good luck