I've made the same upgrade about a year ago also, from the 7 plus to the Xs max. The pros are: (1) better screen. The X has a OLED screen while 7 has LCD I think. The colors and visuals are more vibrant, BUT you probably won't be able to tell the difference unless you've been using the OLED for a while and downgraded or if you're holding them side by side. Also (2), you get a larger display. The screen overall should be relative similar in size, but because they removed the bezels at top and bottom, including the home button, you get a little bit more screen display at those areas now.
The cons: If you're good with 64 GB of storage then it's no problem at all. However, if you need more, then you'll have to pay for the highest storage at 256 GB because they took out the 128 GB option. That and well the price to begin with is pretty a huge difference. Furthermore, it's not really that huge of a leap in difference when comparing with the 7. Appearance wise, it's practically identical other than the lack of bezels. Speed wise, it's a very, very small fraction difference. My Xs is maybe faster by 0.1 sec or 0.2 sec. Basically negligible and even if you add it all up throughout a whole day's worth, you save maybe 30 seconds of your entire day depending on how much you use it lol.
Some neutral points: not really a pro or a con, but with the removal of the home button, you get face ID instead. Some people will say it's better and some will say otherwise, so I'll just list this as a middle ground. It is convenient at times, but the face ID won't always work. If your face.. doesn't look like your usual face for instance, it won't unlock lol. I notice when I first wake up and my eyes are still half open or obstructed with a piece of my pillow/cover, I'd have to lean up forward a bit and try again. Also if you're wearing a mask, it won't work at all. You'd have to input your passcode. And well, I guess there's animojis, but I couldn't care less for it. It's useless to me, but I guess someone out there will list it as a pro so I'll just mention it.
That's pretty much all I could think of on spot. Of course battery life, processor and camera specs are definitely better, but I wouldn't really compare those aspects because every newer generation will boasts the same in comparison to it's predecessor anyway. That's for upgrading from 7 to X though. As for the 8, I've also used it for work before. I really wouldn't recommend upgrading from 7 to 8 because not only do they look identical, it feels no different from using the 7. Price wise, it's definitely way cheaper though. So unless it's a budget thing and your current iphone 7 is barely working or if you really like the 7's design and all and just want a slightly better version of it, then I wouldn't get it. But to be honest, the 7 is still good imo.