It's actually cool but ... it's not the same balance than IC² (I know, BC and its addons are already a bit away from being balanced with IC² but ... with UE addons that's even worse)
I think the bigger problem is that it not only has a different balance, but repeats the same mechanisms IC2 has. With the exception of TE (which has config options to correct it, even if the major modpack makers are too braindead to use them), BC and its addons are doing fairly different things than IC2. They combine together in ludicrously powerful ways in some cases (automated scrapping+UUM production gets nuts without gregtech nerfs, or automated plant harvesting in order to spam generators), but its not a problem of BCs stuff being better, just different.
UE on the other hand, flat out tries to duplicate everything IC2 does, without any regard for balance with IC2. I suspect it'll be really good as a mostly standalone environment (which might be a good thing, it'll help when the way different parts fit together was intentional) once its had more time to grow, but it'll probably never work right with IC2.