Vantaggi
I think it's a pretty good business model, with a lot of upside. Smallish size means you had the opportunity to interact personally with senior mgmt. Relaxed environment, company picnic once a year, etc. You just have to decide if the career track is for you. For me, I had more luck since moving on.
Svantaggi
Smaller company; opportunities for advancement were therefore pretty limited. Your experience depended on the personalities of your immediate superior (obviously). I was lucky in that regard, to work with good people. Also, I was quite junior (my first job) so what did I know about advancement? I will say that the pay, for me, was OK, but not the greatest, and I've found much better compensation packages since I've moved on. Your mileage may vary, but I did hear stories about a few coworkers (one of whom left) who were definitely underpaid. Also my stock option grant was virtually worthless after I left, which put a bad taste in my mouth. Also, if you are young, there was not much chance to interact with coworkers after work for drinks, and so on, most workers were older and had family obligations. For a social scene, and meeting people (not the point of a job, I know, but this does go to work/life balance), I had a better experience once I moved downtown.