I've only ever worked at architecture studios so can't really comment to much on what it's like at a 3D studio.
I've found it quite frustrating at times with architects doing their best parrot impressions, sat on your shoulder constantly making comments and changes, sometimes even talking to themselves. That said, if you are not actually an architect this kind thing gives you much more insight into the design process, which for me personally has taught me a lot.
Deadlines are very tight in an architecture firm. The architects eat into your agreed time and as they're paying you and you're generally sat 2 metres away it's seems to be an acceptable practice. I wouldn't imagine that would happen at a 3D firm to such an extent as you would have a contract with timelines set out. That said, this will help you speed up your work flow so you may very well come out the better for it. At the end of the day you're probably going to end up working stupid hours anyways though so it's a bit of a moot point.
We generally have lulls in workload so you tend to get a bit of a breather between these manic deadlines. Personally I find it a bit boring at times but each to their own.
If you're going to an architecture firm I would check their work and make sure it's of a high quality, as having someone more talented than yourself will help you improve your own work in the long run. I'd imagine most 3D studios would have a plethora of talent, so it wouldn't be so much of an issue.
I'm sure I've forgot plenty but I'll wait for others to reply. I think it'll ultimately boil down to where you want to take your career, and your own personal preference.
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