My experience in upgrading from S7 Edge to S8 Plus is that it is a positive experience. S8 Plus definitely has better battery life than what my S7Edge had though both of them have approximately same battery size. The screen is much larger though the phone is a bit heavier and taller. Would love an S9 Plus but I purchase phones outright instead of through a carrier and the projected pricing I’ve read recently for the 9 series makes it a no go for me. I really like my S8 Plus. Aside from size and strength, the Galaxy S8 Plus has gained Mobile HDR Premium certification which means increased brightness and contrast levels that make it ideal for mobile HDR content coming to Netflix and Amazon Prime Video.
Should you really upgrade from an S7E to S8Plus. It depends. Do you want the Infinity Display which will make your S7 Edge look outdated? Is a rear-mounted finger-scanner workable for you? Can you handle the extra height? It’s definitely a better phone than the S7e for sure, but the question is whether it works for you!