My "Garagedeck" flooring is maybe about 3-4 years old and while I like it and don't have any regrets, it wouldn't have been my first choice. The concrete floor in my garage was in bad shape. Cracked, pitted, and had been patched a few times. Had it been in good shape, I would have just done some sort of sealer and densifier and been done with it. Here's my opinion based on my experience (I have the solid tile- not free flow):
I love the way the floor looks. The installation was fast and easy, and relatively inexpensive (my garage is only around 400sqft). The floor really transformed the look of the garage. Also if I damage a few tiles I can pop them out and replace them.
However... if you're the type of person that does a lot of work in their garage, the tiles kind of makes it a pain in the ***. Any water or fluid that gets on the tile will seep between the cracks and get under the tile and on the concrete beneath it. That's fine for water, but oil or some other fluids would be annoying as you'd then have to pull up the tile and clean underneath it (unless you don't mind just letting dirty oil, etc just sit there. When I'm working on any of my cars or toys in the garage, I first put a thick 10x10 plastic sheet which I tape to the floor. This way if I spill anything, I can easily wipe it up.
I wouldn't do any sort of welding or grinding in the garage unless I put down some sort of protective barrier.
Also, the expansion in the heat is kind of annoying. I went with dark gray tile and my garage faces West. If I leave the door open in the afternoon on a hot day, the tiles start to lift/buckle in about an hour or so. For me its not a big deal as I don't really leave my garage door open often. I left plenty of room around the perimeter to allow for expansion but that didn't help. It almost seems like each individual tile will lift at its center, so the floor takes on a wavy sort of look when exposed to heat/sun. Leaving room for expansion doesn't seem to help because the weight of the floor alone seems to be enough to prevent it from expanding. I put down my floor in the winter so maybe if I had heated up the floor first it would have helped, or maybe a higher quality brand of tile like Racedeck would perform better?
just my 2 cents...