This review is subjective and based on my experience with it. I am fully aware this lens, currently being replaced by the new version with VR, was the working horse for thousands of photographers.
I found one 2nd hand in good condition, because lot's of pros are switching to the new version. For landscape I though this lens would replace 3 primes (24mm, 35mm, 50mm) and my cheap but good 70-300mm zoom that I sometimes use. I just wanted 1 jack of all trade lens. Eventually I might have 1 ultra-wide prime + this zoom to carry. I wasn't interested in the 12-24mm because it is just too wide, big and expensive, besides not having filters.
I had a Nikon AF-S NIKKOR 18-35mm f/3.5-4.5G ED 2nd hand too, wich I sold - a big mistake. I though this 24-70 would overlap with the 18-35mm and it was not useful to have both of them.
But soon I found tree problems.
Problem 1- two big and heavy. I wasn't using it on a regular basis because it is so big. With primes I can stick a 20mm, 35mm or a 50mm and go play with it. This was a great advantage of the 18-35mm f/3.5-4.5G: small and light. I did not value enough this aspect. On a daily basis I was not lugging around the 24-70mm. I noticed I still needed primes to do that.
Problem 2- Not fast enough for shallow dop, portraits and low light. You can get cheap primes that go 1.8, 1.4. This opens a world of creativity and opportunities to use the camera. I noticed this driving around with my daughter. I usually take pictures of her in various situations and I wasn't happy with the results of the 24-70 (adding to problem #1 - carrying something big that didn't do good portraits). So if you want that you still have to have primes and there went the reason I thought was good enough: to replace those primes for 1 single lens.
Problem 3 - Finally had the opportunity to test in landscape. Used it for a couple of days. When I got home and saw the pictures on a big screen I was kind of shocked by the lack of sharpness, specially close to 24mm in the corners. I've read this in reviews but thought I wouldn't be that relevant. This was too me. The 18-35mm f/3.5-4.5G by comparison is ultra sharp costs less than half second hand. It was so obvious that to my taste the shots were ruined.
So there. If I was a pro I understand the great advantage that it is to have the 24-70 range available at all times. The lens is obviously great for that. I would still recommend the 18-35mm f/3.5-4.5G for landscape if one needs versatility. I've read great reviews of the new Tamron 15-30mm. But the thing I found out is that I will always need primes, so using zooms would only make sense for me if I had constraints like shooting things that require fast reactions (events, wildlife, sports etc.) or that don't require the absolute top performance. I'm currently using the 20mm 1.8g and it's just beautiful. Even If I had the 18-35mm f/3.5-4.5G zoom lens I wouldn't get the shots I can get around 20mm and have the versatility to do great portraits.
I quickly sold it. Now sticking with primes + zoom. 20+35+58+ 70-300. I don't regard this as a mistake, but rather as learning. You don't know what you want until you understand what you don't want...
I found one 2nd hand in good condition, because lot's of pros are switching to the new version. For landscape I though this lens would replace 3 primes (24mm, 35mm, 50mm) and my cheap but good 70-300mm zoom that I sometimes use. I just wanted 1 jack of all trade lens. Eventually I might have 1 ultra-wide prime + this zoom to carry. I wasn't interested in the 12-24mm because it is just too wide, big and expensive, besides not having filters.
I had a Nikon AF-S NIKKOR 18-35mm f/3.5-4.5G ED 2nd hand too, wich I sold - a big mistake. I though this 24-70 would overlap with the 18-35mm and it was not useful to have both of them.
But soon I found tree problems.
Problem 1- two big and heavy. I wasn't using it on a regular basis because it is so big. With primes I can stick a 20mm, 35mm or a 50mm and go play with it. This was a great advantage of the 18-35mm f/3.5-4.5G: small and light. I did not value enough this aspect. On a daily basis I was not lugging around the 24-70mm. I noticed I still needed primes to do that.
Problem 2- Not fast enough for shallow dop, portraits and low light. You can get cheap primes that go 1.8, 1.4. This opens a world of creativity and opportunities to use the camera. I noticed this driving around with my daughter. I usually take pictures of her in various situations and I wasn't happy with the results of the 24-70 (adding to problem #1 - carrying something big that didn't do good portraits). So if you want that you still have to have primes and there went the reason I thought was good enough: to replace those primes for 1 single lens.
Problem 3 - Finally had the opportunity to test in landscape. Used it for a couple of days. When I got home and saw the pictures on a big screen I was kind of shocked by the lack of sharpness, specially close to 24mm in the corners. I've read this in reviews but thought I wouldn't be that relevant. This was too me. The 18-35mm f/3.5-4.5G by comparison is ultra sharp costs less than half second hand. It was so obvious that to my taste the shots were ruined.
So there. If I was a pro I understand the great advantage that it is to have the 24-70 range available at all times. The lens is obviously great for that. I would still recommend the 18-35mm f/3.5-4.5G for landscape if one needs versatility. I've read great reviews of the new Tamron 15-30mm. But the thing I found out is that I will always need primes, so using zooms would only make sense for me if I had constraints like shooting things that require fast reactions (events, wildlife, sports etc.) or that don't require the absolute top performance. I'm currently using the 20mm 1.8g and it's just beautiful. Even If I had the 18-35mm f/3.5-4.5G zoom lens I wouldn't get the shots I can get around 20mm and have the versatility to do great portraits.
I quickly sold it. Now sticking with primes + zoom. 20+35+58+ 70-300. I don't regard this as a mistake, but rather as learning. You don't know what you want until you understand what you don't want...