I like them, they just take up a lot of space while they are between being taken out of the box and put back into the box. I like them a lot more now I replaced the nasty light fitting over the dining table with one that doesn't create as much glare on glossier pieces.
I know you can get things that roll them up but they never worked very well for me. At some point I'm thinking I might build a new dining table, that will have a lift-out panel at the very top so there's space underneath to work on puzzles, and you can just put the top back on so you can have dinner guests without having to put the puzzle away.
The biggest ones my wife and I have finished were 1000 pieces. Most of the ones we do are 100 piece. We have a 2000 piece in the basement but it took us so long to try and finish it we needed the table (hence it's in the basement on a board) and never quite got around to bringing it back up. It didn't fit on any of the boards I have, so I had to partly dismantle it to make it work.