Once in awhile you'll get one or two in the group that have cholera or measles but for the first couple years where getting a dozen or so workers can really help staff buildings you need to get everything self sufficient while you wait for the kids to grow up. As long as you are building houses ahead of your population it's usually not a big deal to take them.

I just had a game where immigrants AND special event immigrants showed up, easiliy over 200 in total if not more, all in a matter of a few years. As a result I was able to push my economy skywards and had a great run with over 500 population. Everything was going smoothly.

Then a sandstorm spawned on top of my town and killed everyone and destroyed a third of my buildings. Game over. Literally not able to recover from this due to high population, destroyed storage and massive rebuild cost. All I could do was fire up YT and listen to Darude-Sandstorm, then quit.

In a different game I made a town called "Incest" and never allowed anyone in. It took me forever to get even the basic neccesities going. The situation got worse because I couldn't make my people happy enough to procreate properly. Not enough booze I recon. So they eventually died out of old age, natural causes and the occasional accident. On the plus side, no sandstorm...

I would say it is better to take them in this game than it is in Banished. All the immigrants I have taken in have been educated so far, which was my biggest gripe with immigrants in Banished. It's pretty common for 1-2 of them to have diseases, but diseases just seem like a joke in this game. If I added up all the casualties I have had to diseases from both immigrants and events in all the playthroughs I have done so far, the death toll is 2. So either diseases are underpowered, clinics are overpowered, or I should play the lottery.

Having said that, I would caution that there is a random event that can happen years after accepting immigrants where they get nostalgic for their homeland then pack up and leave. If that happens to you at the wrong time, it could throw a wrench in the works.

With more than 300 hours in the game I lean towards taking even more now. Extra people for trading, work in the mines or sacrifice at the temple. Immigration ftw!