From a .mil standpoint -
We sometimes hooked up spotting scopes to Larue Ipad mounts & Ipads.
Negatives:
1) Weight / Size. Much larger, heavier, more obtrusive combo than just a spotting scope (and whatever else you have on the spotting scope). Increased combat load as well as potential target signature.
2) Backlit. This was mitigated by turning down screen brightness and developing a roll your own screen hood for it and the spotter/observer, but still an issue.
3) Battery Life. Not sustainable for anything other than a one-two-three day mission depending on use. Solar recharging may be a more viable option now.
Positives:
1) Increased screen meant less eye strain as well as a larger sight picture to determine specifics. It was simply easier to see and pinpoint things compared to peering through a scope. Ditto for shot calling and correction.
2) Ability to video record for 15-6 Investigations to prove exactly who you shot, why, where, and when.
3) Can screen grab and work / update a target folder immediately on a separate device.
4) Less training time required to school someone up on it. I can take Joe, give him a quick capabilities brief, a quick diagnostics and troubleshooting brief, and start having him fill in as needed in the event of WIA/KIA or if both snipers need to get on guns for whatever reason.