This discussion isn't a short answer.
I love it. No server hardware to monitor, maintain, support, etc.
No "early in the morning Windows updates and reboots on the server". "or late night". I always do that once a month of clients server. And..that monthly MSP support cost per server is...at least $100 bucks right there, typically more like $150).
No hardware refreshes on servers every 5-7 years.
No Windows licensing there every 5-7 years
No backup system to manage for the server
Less battery UPS needed (don't need to power a server, now just need to power network hardware)
No extra electricity used by a server (surprisingly..a good amount of $ right there each month)
So....addddddddd all that up...factor in that total cost over the time period....
...and now having monthly M365 Business Premium licensing doesn't seem so bad.
I have a thread over somewhere...long thread (needs updating)...but I list out a lot of automated config profiles from InTune. Basically the cloud version of old on prem server group policies. Just enjoyed those today, had a client get a honking new Thinkpad laptop for graphics work, took it out of the box, unbuckled it, created my local admin account. Ran the Lenovo Vantage updates on it...name it, and then joined AzureAD under her name. Rebooted..sign in as her....rebooted again...and sat back and let the magic happen.
*Company Portal app got push installed
*OneDrive automatically engaged...grabbed the user library, files on demand setting kicked in, along with my custom tweaks (warn for mass file deletions, don't sync *.lnk files, block personal one drive, etc)
*Bitlocker kicked in, backed the key up into the computers account in AzureAD
*MS Office push installed, (would have removed prior versions),
*And....the 365 version of WSUS will push out Microsoft Windows updates.....
*Outlook will be pre configured...including the slide bar for "download all email".
*Defender for Business Endpoint...(the kicked up Defender next gen antivirus)...kicked in and activated.
I just did a few custom touches to her desktop...was so quick and effortless for me
And.this lets you consider the computers to be trusted (compliant) devices...so you can better create conditional access policies for them to greatly increase security.