Every single book written (let alone on history) is a product of its times. This is as true of newer ones as it is of older ones. However, it does mean that you will be much more aware of the cultural context of a book written now than you will about one written forty years ago. It is much harder for you to know the mindset, the academic fashions and the events at the time which led to the book being presented in that way. So, whilst newer books will also be subject to this, you will also be more equipped to deal with it in their case than in that of older books.

The other point is that older books will simply be out of date. There are increasing amounts of research going on and, weird as it may sound, we still find new sources all the time. Our cultural views also lead us to see different, although not necessarily better, things in the same sources, which nonetheless has the effect of giving newer books a potentially wider awareness of what could be interpreted in events.

In some fields, you really need to be careful, though. I'm studying Ottoman history at the moment and research has changed vastly in the last 40 years. 70s views are totally outdated and can be full of Western biases. There are many topics which haven't even had books dedicated to them yet. My university library often only has one book on a particular sultan, and then only on the most important ones. Some of these singular books are old, but they're the best available, which really says something about being careful about what you're reading.

None of this is to downplay the skill of past historians, of course. There are some seminal works which were written many years ago. Just consider Gibbon's Decline and Fall, written in the 1770s, more than 200 years ago! His breadth and depth is pretty much unrivalled, but he is still a product of his times and lacking in both more newly discovered sources and more recent insights. Yet he is still hugely valuable.

So by all means read these books. Just remember to take their context into account. Keep a particularly strong eye out for academic and cultural biases and question why they are choosing to see certain things in certain ways. For instance, it was recently highlighted to me to question why there is so much literature, though with particular viewpoints, on the World Wars and not later colonialism, which happened at the same time and was arguably just as important when they were both going on.

As for non-specialist reading... It depends. Because you're reading at a more superficial level the problems don't matter quite as much. Hobsbawn is a very good historian. Just keep their limitations in mind.

Yes I probably would prefer a newer book over an older one in terms of up-to-date scholarship, although I prefer the feel of older books. Ideally, i'd read both.

Just to echo /r/thelithiumcat, yes, you need to be aware of the cultural context of an old history book as well as possible deficiencies due to new research since the book was published.

But if you want to specialize in a particular area, you need to read old history books--essentially, you'll need to know your field's historiography. This is more important in some fields rather than others. (For example, one of the areas I study has had an unusually long history of historians arguing with each other very contentiously and it's helpful to understand what the heck was going on 50, 40, 30 years ago because current scholarship is still influenced by those old arguments.) Not to say you need to read as deeply or broadly of 40-year-old books as present scholarship, but that it's useful to at least be aware of the major texts, the most influential historians, and the historical trends in your own field of study.

I think it's a good general rule of thumb when dealing with history books either old or current that if you don't know anything about a subject and are concerned about reading well-crafted history, that it's typically "safe" to read books from university presses (or their popular imprints if they have them) and to stay away from pop histories.

Look for footnotes/endnotes that show some original research (this is not necessarily a universal when dealing with books 30+ years old). It used to be acceptable to omit footnotes entirely in favor of a detailed bibliographic essay--I love me a good bibliographic essay and some old historians wrote brilliant ones, but it's nearly always unacceptable nowadays for an academic work to omit footnotes.

Old historians will be answering different questions than present historians. (This is more apparent in monographs than in general histories.) Perhaps you'll see a focus on statistics because that used to be trendy, or perhaps you'll see a lack of women mentioned because folks were still focusing on dead white guys. You won't be aware of these different focuses or omissions if you're not already familiar with newer histories. Think of it like old movies. If you only ever watched movies from the 70s, you'd be rather out of step with present popular culture. Likewise, it's almost a social gaffe nowadays if you've never seen the original Star Wars even though it's a movie that's 40+ years old. Knowing old movies seems to be of different values in different genres--for example, I don't think people who geek out on chick flicks have quite the fascination for canon/old movies as do Sci-Fi nerds (maybe I'm wrong on that--I haven't watched a ton of romances). You can watch an old movie and enjoy it and still be aware of blatant sexism or racism. Likewise, you can watch an old movie and identify the origins of tropes or storytelling devices still used in new movies. There's value and enjoyment in both old and new movies and it's best to be a bit omnivorous.

Basically, I think it's A-OK to read old history. (And there's plenty of bad histories published that are brand new.) You ought to definitely read whatever is considered the foundational texts in your field. But it's best to read old history and be aware of what you're looking at, and the best way to do that is to be familiar with the newest scholarship.

I just want to point out that in some fields of history, old books are all that's available. I was trying to add books to the booklist the other week for New Zealand history, and the only general texts I could add were two relatively new ones(last 4-5 years). Prior to that, the most recent was years old.

Sometimes scholarship just isn't completed in a field and you have to make do. Often there are issues with that scholarship, but by and large, the information is still true - the only thing that changes a lot of the time between old information and new is the context in which it is analysed. An older book can be a perfectly fine source, and for general reading, it's excellent. You just need to remember to be critical of it.

The more specific it becomes, the sooner it becomes outdated. Books who handle relatively broad themes, like Hobsbawms Age of Capital, are often the foundation of a given theme. It's great for getting a view on 19th and 20th century history overall. But if I ask a more specific question like, "How did the new avaibility of tractors in 1920 affect the income of the local population of [bumfuck ohio]" newer research becomes exponentially more important because new numbers, research etc. is dug out.

Older books often build the framework where newer, more narrow and specific research gets build in.

An important part is that you always have to keep in mind the limitations of your literature. E.g. 19th century national histories are most often written by staunch nationalists. But source criticism isn't only specific to older history, it should always be an important part. In older books the limitations are just often more obvious.