Ok! Here I am after a week's use. (A720F/DS - Battery in good condition according to battery apps - Coming From Korean Pie - Phone has been working for just over 3 years)
The ROM works smooth as butter, almost stock like experience. Haven't experienced any lag spikes.
Coming from Korean Pie, I feel a tiny bit more battery usage. However considering that a little trade off for all the extra features you get with One UI 2.5, I'm totally fine with it. The only area I experienced inconveniences as others mentioned is the fingerprint unlock. On day 2 trying to unlock using fingerprint, after an unresponsive 15 seconds the display turned on and showed a system UI crash pop up. I haven't gotten any other crashes so far but fingerprint sometimes responds with delay.
Moving over to nightly battery drain, it has improved a lot compared to Version 1.1. On previous version battery dropped by at least 35 to 50 percent on nights and I mostly woke up to find the battery dead. (with Wi-Fi on and connected) With the current build, on day 1 the battery dropped by 20 percent over night which I'd say is due to fresh install and the phone was still adapting to usage patterns. Day 2 and onward these are the nightly battery drain results (in % and also with Wi-Fi connected): 15 - 12 - 7 - 9 - 11 - 8 which are normal.
Extended gaming sessions on this ROM results in the device heating up a bit and after about 10 to 15 mins the gameplay gets framey (FPS Drop), especially if your charger is connected. I disabled the physical navigation keys when flashing the ROM so I can use Game Launcher and Tools. One UI 2.5 also comes with two more game related apps called Game Plugins and Game Optimizing Service. These two allow you to customize how each game can utilize your hardware and help reduce lag. Overall if you're planning on extended Gaming on your phone, this ROM might not be for you.
That's all I have to say about my user experience. If I haven't mentioned anything that doesn't work for you, it could be due to any of these:
it's working for me - haven't gotten to test it yet - you have an A5 and it's an A5 related issue (very unlikely)
I hope it helps you if you're looking forward to installing this Rom.