I recently stopped using plastic takeaway containers and bought 3 square and 3 round pyrex containers with plastic lids. The main reason was because I learnt that some plastics emits harmful toxins. This decision has actually made a difference in my life (no exaggeration!). After cooking, I immediately put it in a pyrex, I serve in the pyrex (because the thick glass retains heat and looks presentable) and I store away the rest in the fridge. After the food is finished, I wash it either by hand or dishwasher and washing has never been easier. Plastic containers are a pain to clean, but not glass!
Microwave and dishwasher safe (lid too), durable glass, beautiful as serving dishes, and easy to clean.
Nothing that I can think of...

I have begun limiting plastic in my kitchen and everyday living, so finding some water and airtight non toxic containers was a must. These are made of glass so can be heated in the microwave or oven, washed in the dishwasher and are very tough. My one year old likes to carry round his one that I send to daycare and needless to say it has been dropped a few times, me watching with heart in mouth, but no chips or cracks. Just for the record, I don't usually allow him to cart it round, but sometimes he retrieves it from his bag before I get to it! These are on my must-get-more-of list.
Made of tough glass not toxic plastic, tight fitting lids, see through

I think its always a good idea to have a few of these pyrex containers in our household. They are easy to clean and definitely would not be bent out of shape after heating one too many times.
Good for storing foods that needs to be microwaved. Apparently this is better than heating up food in plastic containers (courtersy of mum's advice).
Prone to breakage. Handle with care. Priced higher than plastic containers.

I bought this because, being vegetarian I am always cooking seperate meals for myself and this is the perfect size for that purpose. I can cook or reheat a meal in it in the oven or microwave and then if I need to I can pop it in the fridge with the seal on and know that it will keep well. I am sensitive to the subtle (nasty) flavour that some plastics can leave in foods so pyrex is the best choice for my food storage. I have also found that it's just the right size for microwaving those frozen lasagnas and other frozen 1 serve meals. Great buy...
Tough and very versatile.

we got a set of 4 from big w, excellent value.
pyrex is great not just for storing left over food, but for baking as well, and if there are any leftover, just put the lid on and put it in the fridge!
from freezer to oven - no fuss

I quite like these Pyrex containers. They are very handy and are extremely versatile - they can be microwaved (and the lid doesn't warp or anything like some lids do) and are dishwasher-safe. The fact that it's glass means there's some risk of little kids and breakage, but if you just exercise some common sense it should be fine. Also, glass (as opposed to plastic) is great as there is no annoying smell from plastic, and food smells don't stick to the container either.
Good quality, very handy for storing food for picnics and for keeping leftovers. Very versatile.
Pretty much none...