I have a Q1000; it's well contructed and works pretty efficiently overall, but is less satisfactory at 'grilling' steaks (than chicken or pork cuts). The porcelain-covered grates can be difficult to clean, and the inside of the grill 'box' needs cleaning after each use. (I know that some may not do this, but I don't like the grease buildup.) I use a 14.1 oz. propane canister because the 'fit' is better with this than with a 16.4 oz.
The biggest issue for me is the same as others have mentioned, i.e., if compartment space is limited, the unit can be difficult and awkward to store, primarily due to the rounded lid. I remove the lid, store it in one compartment (with the cotter pins in a little zip lock bag), and store the bottom of the grill in another compartment. This is a bit of a nuisance, but it's doable.
(Note that the Q1200, the Q1000 with fold out 'shelves' and a thermometer in the lid, has a slightly *higher* lid than the 1000.)