They're kind oh like snakes when you think about handling - some species are known to be a lot easier to handle than others. For instance, the g. Rosea would be more like a ball python, whereas things in the poecilotheria family (the Indian ornamentals) and any of the old world tarantulas would be more like GTPs. Of course there are always exceptions, but usually that's how it is.
The vast majority of tarantula venom is really not that potent, especially the new world tarantulas. Most of them will cause a little discomfort (itching or burning), and depending on the potency of their venom it will last from a couple days to maybe a week. Some people can be very sensitive to tarantula venom (they have a more intense reaction) and there are a few old world species that have medically significant venom that you'll want to have checked out if you get bitten, but I don't think there have actually been any deaths associated with T bites, even from those who are more sensitive.
The actual damage from a bite besides a little redness, itching and a bit of swelling (though they don't always inject venom, so it could well be a dry bite) is usually not that bad, unless you get bitten by one of the giants because they can have fangs that get up to a little under an inch long...
Sorry if this is a little long haha![]()