For most of my career I have often ping-ponged between big and small companies. Large companies offer security, and they are generally slower, more relaxed environments, but I actually prefer working in smaller, even tiny organizations.
For one, you don't have to wait for people to do stuff. If it is going to get done, then you're probably the one to do it. Nothing is worse than having to wait, only to find out that the work done was shoddy. I'd rather just go at it myself, accepting that it may not be perfect, particularly if I've never done anything like it before, but it least it will get completed.
Process, or at least the simplicity of it is another reason why small companies are great. Many people who have spend their whole lives buried in big institutions have some sort of strange mystical faith in their underlying process. The bigger and more overly complex it gets, the better they seem to like it. In a small company, you quickly learn to only do work if there is any real value in it. If it is a waste of time, you drop it. In a big company, all sorts of people do all sorts of stupid make-work tasks, over and over again, as if somehow repetition will magically add value to their time-wasting. It's kinda creepy, in a sad way.
Communication. In a big company people can spend nearly forever getting around to saying what they are trying to say. Some might even pride themselves on an ability to spend extra long to release as little as possible. In a small company, if you've got something to say, as Johnny Rotten screamed "f*cking say it". You don't waste words, you don't beat around the bush.
Politics in big companies are horrid, stupid and insipid, with the various parties trying to outwit each other wherever and whenever possible. At best it's clever, but as an old friend loved to say "monkey's are clever". And mostly it turns out that the ones who think they are best at these brain-dead sports, are usually the ones most frequently tricked into thinking they've won more than just another bad deal. Politics in a small company is usually just friction between the personalities. Mostly, once it starts to get bad it resolves itself pretty quickly (usually by someone leaving).
Bullsh*t in all its shapes and sizes is a landscape feature in large companies. Big organization obtain big mountains of it. This includes stuff like "mission statements", huggy feely corporate messages, performance reviews, messages from the top and any other career or worldly advice that the robots in management are told that they should tell you in order to pump up your floundering morale and to help exploit more of your time. After all, if it comes down to a choice between you and some executroid's bonus, you don't stand a chance in hell, but otherwise they really "are" looking out for you best interests. At least in the little organizations, there is no time for dispensing this putrid stuff; it is a lot more honest.
Basically, while you are insulated from anything but your core job in a big company, it is also easy to become detached from the reality of what you are actually doing. You could spend your entire life hidden behind massive walls, only to realize that you've never even witnessed but a tiny fraction of the reality of whatever you are trying to accomplish. If you've ever wanted to try every related position, experience all the angles, and get down and dirty with a lot of different, but interesting jobs in your industry, then a small company is the place to be. Little companies can't afford specialists, so you are able to get your hands into more aspects of the operations. Little companies just don't have the same 'turf' problems that plague the big ones.
If you've stayed too long in corporate-land, it becomes nearly impossible to leave. Like an over-protected child getting out for the first time, many poor souls that grew too accustomed to their cushy lives have met crushing defeat when exposed to the real world. Most people are not cut out to survive a small company, it is just too raw for them.