I'm a big fan of microbrands and have 6 different brands. They make up most of my collection.
There is no official definition of what is a microbrand and everyone has their own interpretation when it comes to it, here are a few criteria that a brand usually has to meet:
1) They have a small number of full-time employees or just the owner, who runs everything.
2) Most of the production is outsourced.
3) The movements used are not produced in-house.
4) Sales are done primarily online with very limited or no brick and mortar presence.
5) Only a relatively small number are produced of each model.
I have had good and bad experiences, the quality is usually higher at the price point than mass produced and you get more for your money for example a better movement and you're not as likely to see someone else wearing one. I have a few limited editions, one is limited to 50 and the other at 100 worldwide, only 6 came to the UK so it feels a little more exclusive. The owner usually has a Facebook presence so can be contacted directly, but is sometimes slow to respond being the only person in the 'company'. The movements are usually Seiko, ETA, ST-P, Sellita or Miyota so I don't imagine they are hard to fix/replace if anything goes wrong and the company does not exist anymore.
It's usually the customer service/communication that lets some down. For example Crepas/Almirante took weeks to answer my emails about an issue with a screw bar, the watch was eventually collected by them (at their expense) after further weeks of waiting for replies and replaced. E.C Andersson (supposedly higher end) were horrendous at replying, stating they had been busy! It was agreed the watch would be returned, at my expense and it was left at the sorting office in Sweden for over 10 days by them. Still no replies to messages even when sent to their members only priority email. Sometimes the wait for a new model can be long one.
There are exceptional brands though, Gruppo Gamma are amazing, Zelos, H20, Hamtun, Boldr from my experience and I've heard of others that are just as good. It's worth joining the Microbrand Watches Facebook page for info, posts from the owners, great pics, offers and sales.
So it's a yay from me, I think everyone should give them a serious look at and it's also helping a self employed person or independent company instead of a massive all swallowing giant corporation.