IB is great as long as you do not have to deal with service. Peterffy said once, they think they made a mistake if you have to contact them (praphrased from memory).
Most things work automatically with the corporate action tool. For example international tender offers can be tendered with IB most of the times on the deadline day, my other brokers sometimes require at least 7 days advance decision and some even in written form (print/sign/scan or send via post). Even non-traded warrants can be excercised without calling in person, also partially with their tools. TWS is quite intuitive and has even more functions than I need. They have more order types than my other brokers. One weak point is the safety of money deposits. European customers after Brexit have very low EU insurance now (USA customers have better insurance).
One bad example: Account has been short calls on GME and in TWS purchasing GME shares was blocked (temporarily), which would have made the trade a fully covered call (risk reducing). I do not know the reason, but sure cost money to close the option instead at the then higher price of GME after recognizing this. I would not use them for any critical position, but many things are very time efficiently dealt with via their computer system and cost is low in my opinion.
other weak points:
-If you have non-traded options/warrants/preferreds, which are excersisable, they will not even update it to intrinsic value automatically making the reports relatively useless.
-Withholding tax reclaim (most often from dividends) is not supported and they provide a limited number of tax forms only at extra charge (which is more expensive than local alternatives in my case, who can even file paperwork automatically at extra charge).
Overall, still the best for many use cases in my opinion (European perspective).
