I've been using a Blackstone Griddle for about four years now. Originally had a 36" unit that I used both at home and camping. It was a beast to move around though and the only place we could store it was under the dinette and it was a VERY tight fit and very awkward to load and unload.
This summer for our road trip we elected to buy a 22" unit to be more portable. It also has a lid and a stand with adjustable legs making it easier to setup in camp. I've only used it at the home so far but I'm quite pleased with it. However, I was actually surprised how large even the 22" unit is. For portability sake, I might have gone with the 17" if I had the chance to compare side by side. We do usually go camping with family so having the larger surface area is good for us but if I was full timing and it was just two to four people, the 17" would be the way to go.
In regards to it's use, it makes cooking SO much easier. I love not dealing with flairups and excessive smoke. Yes, there is splatter from your cooking oil so long utensils are highly suggested. Once you get a good seasoning on the surface, you can cook without fear or sticking. It also cooks a lot of food fast in my opinion. Whereas a BBQ has not spots and cool spots depending on how close to the flame, the griddle does a much better job at distributing the heat. That means your cooking area is literally edge to edge.
For purchasing, Amazon has them but I think Walmart actually has a better price on them. Well worth the cost.
One last thing... The griddle surface is heavy. If you transport it while on top of the bottom portion, you need to support the Griddle piece where the four small pegs mate with the bottom part. I failed to do this on my 36" unit and the weight of the griddle was enough to bend the thinner metal on the bottom gas assembly when it was being bounced around in our cargo trailer. The 17" unit might not be heavy enough to have the same problem but worth adding a piece of cardboard between the two pieces while on the road to avoid the issue all together.