Ads should be A) visible enough that players know they exist as an option and B) subtle and nonintrusive enough that the players doesn't feel like they are having the advertising shoved down their throat. This rollout here in FoE has done a petty good job with this balance; it's clear some thought was put into the implementation ahead of time, which I appreciate. I do have a few comments in feedback, however. I've had the ads since they were first introduced for some players, so I've had some time to play with the feature.
Aid All. This is great. It adds a really nice feature option, it's easy enough to locate, and it doesn't pop up in your face demanding attention. No criticisms here, only a potential bug: I have noticed that the aid all doesn't play well with quests requiring mo/po, the quest counter goes all screwy while the aiding is occurring, jumping up and down randomly.
Tavern Boost. This is a nice little feature too. I think it will be especially useful to newer players who have their taverns less built up, but more developed players also might appreciate the little extra buff at times. However, unlike the aid all, this one DOES pop up in your face demanding attention. The tavern should default to the table screen as it always has, with the ad buff screen another tab you can click when you wants boosts, same as the main boosts tab. It is unnecessary and frustrating to have to click away from this screen every time you open your tavern. It's easy enough to find and use without it coming up by default; anyone who uses their tavern boosts normally will see it right away and know it is an option.
Treasure Incidents. This is the one I have a serious complaint with. The basic feature is nice, especially for newer players who could use the little extra rewards from these. BUT, these little purple treasure chests are so UGLY cluttering up the landscape all the time. They ruin the aesthetic of the cityscape. At the moment there are only two ways for a mobile player to get rid of them. A) watch all the ads or B) log into a computer and click them in the browser version. You want your players watching the ads because they are given positive motivation to do so (the tavern boosts, the treasure chest rewards, the time saved with the aid all button), not because they feel like they are being punished if they don't (with an eyesore, in this case), which leads to frustration and people eventually moving to other games. There are two simple ways that immediately come to mind to fix this problem.
1) Add a "No Thanks!" button next to the "Watch Ad" button that dismisses the incident. That way if you don't have time to watch the ads or don't want that reward you can get rid of the incident and have a clean landscape until your next round of incidents.
2) Make the "treasure" ads like the carriage for FoE plus or the winter event reindeer sleigh: a single treasure chest in a fixed location that you can click on and watch the ads available for you that round to get the rewards. When you've watched them all, clicking the the chest will give a message saying "no ads available at the moment, check back later" or something of this sort until the nest round of ads becomes available. This is my preferred solution, since it is far less intrusive aesthetically than the current batch of chests scattered across the landscape, and it fits with the existing system of fixed locations outside your city you can visit (such as the castle, tavern, settlement docks, and even the FoE plus carriage). However if you are determined to keep the treasure ads specifically as "incidents", solution 1 would still be an acceptable fix.