I have a lot of experience with Lowell's old mill buildings, being an artist studio renter and a loft tenant for over 15 years. Here's my take on them, the good the bad and the ugly (without naming names)

There are some places that are advertised as lofts but they're not lofts. At all. They are very cramped dimly lit 2-story dens that are very expensive (well, now... not when they opened) for what you get. But their location is great, you can walk to everything.

There are some lofts that are moderately to very new and are actual lofts with nice amenities (or at least were nice about 8-15 years ago when they were new), and some even advertise themselves as "luxury lofts", but the complexes are so enormous and have so many units that nobody has any sense of responsibility or community to one another and people are noisy, violent at times, litter everywhere, make messes in stairwells and so on. Some of these places are headed towards being horrible places to live within the next 10 years. Be on the lookout for how the grounds are kept. Are the sidewalks clear of ice? Is there dog poop anywhere? Do people loiter outside and disregard "no smoking signs" because there is no consequence? I would consider these red flags... while not indicative of an actual ongoing problem, they signal a slew of potential problems if not rectified or solved.

There are some lofts that have no Section 8 housing agreements (lower income) and so you could consider these places somewhat more discriminatory in that in order to move in you pretty much need to have a job that makes the kind of money where you can afford it. In some way, this does help with some of the problems you see in the types of places I mentioned in the paragraph before. However you still have other problems. These units tend to be very large "giant boxes" so-to-speak, and so, sure, they are more "pricy". They also have cracked concrete floors and ceilings in some cases. These are very low-frills places to live. However, you will not find a better deal per square foot in Lowell or even the greater Merrimack River Valley area as far as I can tell. Think about it like this: if 700-1200 sq ft. apartments in Lowell are renting for $1200-1600 a month, you can get 1600 sq ft. for a couple hundred bucks more at this place. That's a hell of a lot of space which you can do whatever you want with. You will not find that much square footage in a relatively safe place near amazing amenities as far as I can tell. The only requirement is that because one of these places I'm talking about is owned by a major Boston-based arts non-profit, you have to be in the arts/creative (including music, architecture, dance, performance, theater, etc.) industry of some kind. But there are some which have extra rooms, better amenities, nice wooden beams, awesome parking, but they cost a lot more per square foot.

That said, almost all of these kinds of places I've talked about have significant to serious noise issues. Developers will go on record and tell you that "they were all built at least to Massachusetts at minimum sound-reduction requirements". However, those minimum requirements, i suspect, were determined based on structures that were intended to be housing. And not former mills where the 1st floor's ceiling is, literally, the 2nd floor's floor. That means if you live below someone, you will hear their high heels, chopping vegetables, and I kid you not... sweeping. Because sound travels better through solid objects. The mills weren't built with sound isolation between floors so you no matter how much dampening you put in the drywall between units, you will still get a ton of contact noise traveling from 2nd to 1st floor.... and sometimes even across units because of metal beams that go through dozens of units.