Just my opinion:
I like factorization a lot, like the barrels, like the router, and even like it's ore processing mechanic.
No, it is not as easy to set up as other ore processing systems, and, yes, it is pretty expensive to build, but I like the logical steps that are not only a bit less loosely based on realworld ore processing but also allow you to stop at any point in the processing chain, take your ores and just smelt them with the bonus yield you got.
I do not (yet) use FC's ore processing for all my ores, I just use it for my rarer ores, the ones that I do not or do never have enough of - and it's wonderful for that.
I believe that there are three key issues that irritate people when they first try to use FC's ore processing - the expensiveness, the hard to automate mixer and the crystalization process taking 20 minutes.
I do not believe though that these issues are the reason why FC is not compared to TE or IC2.
I believe that the reason for that is that Factorization doesn't feel complete.
If you go the TE road you get all the machines you need to work together with a bunch of mods, making TE nearly indispensable when working with Buildcraft, Railcraft and/or Forestry.
If you go the IC2 road you get access to a whole ecosystem of mods that not only give you all the machines you need and all the power sources you need to power them, but also various tools and accessories.
If you go the FC road though you practically only get the expensive, hard to automate and slow ore processing. Most of the other stuff in the mod does not need those machines and thus doesn't feel like it really belongs to that ecosystem.
After having laid quiet for some months, Factorization is changing again though, and some of those changes have already positioned it much better then it was before.
Now I can use solar turbines with Railcraft steam and can produce steam for Railcraft machines using solar steam boilers; and there's a bunch of other new stuff that I haven't tried out yet.
So, I believe that Factorization may grow to an extent where it will provide the player with a more complete infrastructure and give him enough incentives to actually use it.
When (or if) Factorization has reached that state people might be starting to compare it to TE and IC2; before that point any comparison between the three can only target isolated parts of the mods, never the whole experience of using the respective mod, as Factorization is not yet complete enough to offer comparable content.