Pros
Since the company is smaller you get to experience other parts of the business that you might not learn in a larger setting. You get to know your coworkers well since you are with them all the time. Good place to start if you have little to no experience. Health insurance and 401k match are excellent. Bonus plan was okay, though seemingly impossible to attain at times.
Cons
Long hours without warning - you might not know that you will have to stay late until more than halfway through your shift. 40+ hour weeks are the norm not the exception. As a result work-life balance is pretty much non-existent. The pay, vacation, and holiday benefits are very poor for a laboratory. Old equipment or limited quantities of equipment means you may have to wait until someone else is finished with it, or wait for a replacement. Some people in a leadership position have little to no management skills. Lots of stingy money talk on a regular basis. If you call out sick or go on vacation, everything is likely to be a disaster upon your return.