I am based in Australia and use TS for demo trading FX, but use another broker for real trading, as I have an indie that works well with TS.
I can only give you my view on an FX based account.
6 months ago I opened an account with $2k, just to get their platform and data for free. ANZ is my bank and they were puzzled by TS's wire instructions.
I double checked with my account manager at TS and he assured me that their instructions were ok. No, I am not exaggerating when I say it took three weeks for the funds to be credited to TS.
TS account manager did not know where they were, in the pipe line. ANZ contacted them twice to try and trace the funds and never received a reply from TS (ANZ is a major Australian bank !).
Then magically TS informs me that funds have arrived (after weeks).
Since then the platform has been stable and it does what I want it to do.
Learning TradeStation - Trading Options with OptionStation Pro
However, my experience is limited to FX and I have not withdrawn any funds. From others, I hear that they process wires quickly and one FX trader I know has a large account with them and with FXCM (UK).
When the CHF debacle happened, he pulled all his funds from FXCM, but kept TS account open with significant funds.
Hope that helps