I've noticed some serious problem using this firmware.
Although WiFi reception signal strength seems stronger, output power is actually much lower. For example, I have two wifi bridges (2.4 and 5Ghz). Using the official 2.01EU firmware, Dir-825 status page displays those bridge reception signal as 18% and 55%. The new firmware shows them as 48% abd 87%. No problem so far.
Unfortunately both bridges report much lower DIR-825 signal strength on their side (20% and 60% before, 4% and 21% now). A lab field meter I own shows exactly the same; Using this new firmware DIR-825 output power is much lower (<50%) than before.