I've never ever understood the meaning of over-powered when people used it on a game that is primarily non-competitive. Plus, it's a mod/mod pack that comes with config files. Don't like something you see? Tweak it. Don't like the concept of it? Remove it. The server you play has those mods and/or the "ezymode" configs on? Quit it and start your own server. In my own opinion, vanilla Minecraft is way harder, and most mods are OP. But mods are fun(most anyway)! And any mods you do not get enjoyment out of, you can remove/disable/reconfig it to you own liking!
Sure. I think DartCraft gets so much attention even from people like DoctorOr who are notoriously hardline about such issues is because in essence the mod has a lot of great ideas and features. The problem is that you can amp any one of those features to a pretty ridiculous degree and end up with situation where a Wither drops 60 nether stars or somesuch nonsense.
For example, DartCraft's flight? Not OP. It's well executed, somewhat different, and reliable. It is weaker than most other mods flight options, but very still very useful. Similarly, the interaction of Wing with Water? Neat! A good plan, even!
DartCraft's engines are sort of bad design, because the reality is there is no reason to use any engine but the force engine. But boilers and reactors exist, so... I am of the opinion that in actuality DartCraft's engines are how BuildCraft's engines
should work. BuildCraft has been getting a lot of criticism for not appropriately balancing things to compensate for various other changes lately. This may be one of those places.
DartCraft's IC2 upgraded drills are very bad design because they destroy the entire tool design space. The only reason you don't use a force Drill is because you are deliberately avoiding using DartCraft's stuff in preference of the more fiddly and custom Tinker's Construct tools. And you CAN beat DC's tools in certain situations with TiC, but these situations are all sort of secondary to they "plow through the world with fortune 500." It is difficult to imagine how you could make a better hand tool. In some ways, the DartCraft Power Drlll is much better than the destruction catalyst ever was!
DartCraft's Armor is a mixed bag. Some of the stuff seems to freak people out, but it's hard to argue MPS isn't almost always better, and it's not like DartCraft's armor is accessible early game.
DartCraft's teleport rods and buff rods sort of leave me upset with myself. A teleport belt is amazing and fun and really helps builders, but again it smashes the entire teleport design space. Even dimensional doors look fancy and elaborate in comparison, and dimdoors WERE the op inter-word choice for a long time. But I still like them. I submit that they could be made to work, but they should not be able to accept repair upgrades.
Probably the most insidiously strong parts of DartCraft is the armor's force punch, which can do really silly things when you set it up right. Also subtly way wrong is DartCraft's Bane power, which not many people realize what it can actually do but when you do it's pretty absurd.
One place where the rest of the world needs to catch the flip up with DartCraft is its backpack system. I will personally roll up a newspaper and bop you on the nose if you call them OP. They are a very good idea, they work very well, they basically do what Forestry should have done, but hasn't for want of time and technical reasons; they make useful backpacks. Dart's ongoing decision not to make them part of an automated system is probably also good.