Pretty much everything, but ESPECIALLY their customer service. They're horrible and clearly do everything possible to protect themselves and don't care at all about their users.
Anyone who may be considering TradingView should be warned so they don't get completely screwed over like I have post the 30-day trial.
I had signed up for the trial to check out all the bells and whistles. At the end of the period, I hadn't really used it much, so intended to cancel. With 30 days being a long time, I forgot to cancel before being charged for the full year ($600) and, when I received the email from their accounting team with the invoice, I immediately tried to contact them. I checked their refund policy and they said that if you requested a refund within 14 days of an annual charge, they would honor the request. So I replied back to the accounting email I received requesting this. I also sent them another email to a different email address I found requesting the same. I searched everywhere for a phone number thinking it would be easiest to call, but didn't find one anywhere - not even for customer support (found out later that they have an online ticket support system, but it's pretty buried and there was nothing that clearly pointed me to it).
After a time, I hadn't received any response from their accounting team or the main email I had sent a message to (both emails went through with no issue - I never received a reply - automated, undeliverable, or otherwise) so I filed a dispute on the charge with my bank. Completed the dispute form showing that I had requested a refund the only way I knew how to and within the timeframe their policy had said. The dispute was then denied and they said the company refused to comply.
I finally found the online help desk submission and uploaded screenshots and other things to show that I had requested the refund within their time, etc. only to have them inform me that I had done it incorrectly and, because I had submitted a dispute with my bank card, that apparently nullified my ability to request a refund at all.
In an age where we have a crazy amount of options available, I can't fathom a company that is so challenging to work with and so unclear in their communication and so unreachable to then take this a step further and actually punish their users rather than to be accommodating is just unfathomable to me.
They may be great in terms of functionality for charts, trading/market info, etc. but frankly I don't have any interest in doing business with a company as unforgiving and inflexible with their user base as they clearly are. It says a lot about who they are as a business - it's obviously far more interested in making money than they are in serving the people who keep them in business.
Anyhow, just wish someone had told me this prior to getting stuck with the trial and a full subscription payment of no small amount so felt like it would be a good thing to share with others.
I definitely will not EVER use them again. Review collected by and hosted on G2.com.