Should be able to get a good workout with high enough resistance and a good cadence. I find that my HR and watts are a bit higher on an elliptical (at the same PE) relative to treadmills due to the upper body load.
Not a huge fan of ellipticals, but find them useful when dealing with injuries that limit my running.
I love them - started using them when I had a toe injury and discovered that my running fitness actually improved during that period. Now we have our own elliptical at home. Elliptical allows me to add more time and intensity in my running safely, without the pounding, wear and tear.
There’s a wide variety in quality of ellipticals. Most gym ellipticals will be very good, but try out different ones at your gym if they have multiple types. Get your cadence up to at least 180. I average around 190 and will do intervals over 200. I guess there is a bit of a learning curve with technique and muscle recruitment but I figured it out pretty quickly myself. Tried an arc trainer a few times and couldn’t come close to feeling good - regular elliptical makes sense to my body though.
Google something like “elliptical technique for runners”. There are some good articles out there with advice for people who are replacing running with elliptical.
+1 for using ellipticals. I find I can put in a lot of hours without the wear and tear, but also I can watch mindless TV. I usually watch Band of Brothers every couple of years, and watched the Walking Dead while on it. For me, in the winter I’d rather elliptical than run in the snow and risk injury.