They are't unplayable (or weren't until 2.2.4 broke purging), but they are significantly weaker than organic empires.
Things you should do:
1) Take exploration first. This is required. Don't colonize anything until you get the +2 pops on new colonies from exploration. Get to 5 pops on newly colonized worlds immediately by transferring from your home world and other colonized planets.
As an example, if you colonize 3 planets at similar times in the early game, resettle one pop each from your homeworld and 2 of the colonies to the 3rd colony- this will get you to 5 pops on that colony immediately and double the growth rate on that planet. This is why the additional pop from exploration is so important. Then wait for the next pop growth cycle, and transfer to the next colony to get to 5 pops. Then finish up the last colony to 5 pops. Do the same thing to 10 pops, where you resettle all pop growth from all colonies to a single planet to get it to 10 as quickly as possible. A pop 10 planet has triple the growth rate compared to a new colony. You do not want to let the colonies grow to 10 pops naturally without resettling. Getting to 10 pop ASAP is imperative, as the base growth rate for robots is abysmal.
As an aside, I generally don't colonize anything until my homeworld has reached 35-40 pops- that will let you have 2-3 alloy foundries and enough energy districts to have a good surplus, which is necessary for all the resettling you're going to do at the start. 40 pops is also means that the planetary administration tech is good to take if it pops up early, as that will also boost your pop growth rate even further.
2) Turn off coordinator and hunter drone jobs on new colonies until they reach ~10 pops. The hunter drones aren't needed until then, and the coordinators a big energy sink that makes colonies an economic blackhole at the start if you don't disable them. If you do this and make your first couple districts energy on new colonies they will be energy neutral/slightly positive from the start! Once you hit 10 pops you can reenable those jobs and it will be fine, but you need a few pops working as technicians first or your economy will tank early on.
3) Try and only have one dedicated shipyard starbase, and make every other starbase filled with solar panels early on. You need those solar panels. Unless you have a scary enemy nearby, try and avoid wasting any starbases on defenses at a chokepoint, because you don't have the energy to spare. Every starbase that isn't on solar panels is costing you a ton of energy. Organic empires have a lot more flexability with their starbases, and can afford to waste a few on things like anchorages or defenses at key areas, but you can't. You need more solar panels. Always more solar panels.
4) Only play with 2.2.3. Patch 2.2.4 breaks pop displacement and gives you the genocide penalties for any type of purging, which means all ME play like exterminators, but without the bonuses. This is... not good.
Sadly, what you should really do though is #5:
5) Play an organic empire. They're just way better. Against the AI it doesn't matter, even on the higher difficulties you can play ME just fine. It's just you'd be twice as strong if you were an organic empire instead of ME.