The biggest issue that everyone has seemed to have with the HTC One M9 this year, has been the camera. HTC did go with a 20MP sensor this year, instead of a 4-megapixel UltraPixel sensor. But it seems that didn't solve the issue completely. We've already seen an update or two come out to improve the camera of the HTC One M9, and now it appears that HTC has sent out yet another update. However this one is also said to improve the battery as well.
As far as the camera goes, HTC says they improved the following:
"Greater auto-exposure balance to improve overexposure, so images don't look washed out. Reduction of blur and noise in low light, so images are clearer with better detail. Reduction of yellow/green hue in photos, so colors appear truer to their actual hue."
HTC says in terms of battery life, the update should improve usage when using YouTube and Facebook. Which are the two most popular apps on Android, and also the two that will use up the most of your battery life. So there's that. There's also an update on the heat of the Snapdragon 810. The update brings "Smart charging thermal improvement, which means your phone will stay cooler when it's being charged". So not a huge update for the heating of the Snapdragon 810, but better than nothing.
The update appears to be around 526MB in size. Now this is likely only heading to the unlocked models or international models right now. Which means if you bought your HTC One M9 from Verizon, T-Mobile, Sprint or AT&T, you'll have to wait a bit longer. We all know how the carriers like to review these updates and make sure they are okay before sending them out to their users. So if you're in the US on a carrier variant of the HTC One M9, I'd say you'll probably get this update in a few months, unfortunately.
The HTC One M9 is a pretty decent smartphone actually. While yes it runs the Snapdragon 810, which isn't perfect and does have some trouble with heat, it's still a great smartphone.