I have one of these cages for my single boar Rodney. Firstly, the ramp that comes with it will definately need altering as it is basically a plank of wood, very slippy for piggies. Before my other 2 boars Bradley and Barney had an upgrade they were in this cage, on using the ramp they ended up sliding all the way down at some speed before hitting the bottom. I covered the ramp with carpet for grip and added sides so they couldn't fall off.
The water bottles that come with this cage are a waste of time in all honesty, I found them to be of very poor quality, they leaked and the plastic they are made from isn't clear so it can be hard to see the water level. For cleaning, the top level is very easy to access as you can access it from the top, a door at the front and also the whole front side lifts up too. The bottom level, however, is harder to clean as the only way to access it is buy using the door, I find as I am a small person with short arms the only way I can clean in to the corners is buy actually wriggling through the door and into the cage to clean.
The amount of space is great but I would say that it's really better suited to 2 pigs rather than 3, you could fit 3 in there but for 2 it offers a good amount of space to run around in. Having 3 pigs will obviously lessen the space and it could become a little cramped. The cage offers great ventilation and the houses that come with it are great as they just clip on, I have had mine since October and have a small split on the floor of one of the levels.
I would recommend it though, my single boy loves his pad.
P.S: Have you thought about using a run as a cage? You can get runs with roofs and without, they are sturdy and come in a range of sizes plus they are quite a bit cheaper than commercial cages. My other 2 boars are now living it up in a 8ft x 2.5ft run.