Factorization is an odd duck in that it basically a self-contained mod. Many of the features that seem lackluster in FtB would be very powerful in an otherwise modded game. It still brings a lot to the table, I wouldn't want to play without it. I'd say the thing I like about it the most is that it reduces the number of clicks that you have to do to perform basic actions.
Pocketcrafter: This is a matter of personal taste. Just as you can't understand why some people like it, I can't understand why you don't like it.
When I go on expeditions, I'm always running out of simple consumables or discovering that I need some basic tool that I don't have. The normal way to deal with this is to fish a Workbench out of your inventory, put it on your hotbar, place it on the ground, and then click it. When you're done, you either have to retrieve the bench or resign yourself to crafting a new one the next time you need something. With the Pocketcrafter, I just push J (or whatever button you choose to bind), and BAM you're ready to go. Yeah, sometimes you have to dump stuff from your inventory but I mind that less than fiddling with the Workbench. Moreover, the Balance feature is so good that I will frequently use the Pocketcrafter even if I have a 'real' Workbench right in front of me.
Bag of Holding: This thing is great. It seems kind of weird and counter-intuitive until you realize that it was designed to have the minimum number of clicks to operate. Once you understand what it's trying to do, it's amazing. There are no subscreens or extra GUIs to fiddle with, and it works even if it's not on your hotbar. I like it so much that I rebound it to the side button on my mouse. It also effectively expands your hotbar, which is huge.
The best way to use it is to place it on the fourth column from the right in your inventory. That way, it doesn't scramble your inventory every time you use it. If you upgrade it, you want it move it one column to the left for every extra column you get. If you use it in this manner, you will quickly grasp how clean and easy it is to use.
The Bag of Holding isn't an either-or choice with the Forestry bags. You use both. The Forestry bags are great, but they are a huge pain to retrieve things from unless you resign yourself to always having them on your hotbar. The BoH doesn't have the raw storage but lets you instantly access items with a single keystroke without even having to open the inventory screen at all.
Wrath Lamps: The cost is only a problem if you are only making one or two of them. A diamond block makes 12 shards, and each shard can make a lamp. That's not so bad. Wrath Lamps are nice when you want to light a huge area but don't want to clutter it with torches. They are also really good at lighting up jagged cliff faces and other bits of difficult to navigate terrain.
Barrels: These sometimes save space, and sometimes require more space. It depends on what you're sorting. The main appeal for me is the easy labeling and the one-click interface. No searching through chests, no changing GUIs, and no drag-and-dropping.
Ore Multiplication: This is the weakest part of the mod. It would be okay in vanilla but in FtB we already have much easier methods that give almost as much. An Induction Smelter grants a +125% bonus to every resource that can be Factorized, and can be built almost immediately. You have to accept the multiplication process as a self-contained mini-game. It's only worth doing if you enjoy fiddling around with it.
