Not much. SFMC/ET leaves a lot to be desired. They were one of the first to be able to be personalized and have dynamic content.
The folder structure for organization is good.
They are one of the few that offer a heat map of clicks for your one off instance deployments.
Almost everything. Starting in ET as mentioned with dynamic and personalization was new to email. To be able to do it wasn't easy. With the addition of Content Builder it has become easier, but the sync to your legacy doesn't work, though they came it does.
The customer support, even at the enterprise level is really bad and not helpful.
They have campaigns but other than for organization they don't mean much.
The reports are limited, especially for triggered sends.
The ability to customize the preference page layout is not available. All you cam do is in admin change colors and logo.
The entire dashboard is not attractive or a good UX. It doesn't appear othr than color and embossing the new content builder is an improvement.
I know they are doing alot with updates to Content Builder, Journey Builder and Audience Builder but they are still behind the leaders in the industry.
At this point no. I have migrated 3 times away from SFMC.
I will say if they can figure out the connectors to their parent product they will be much better off.
They are headed in the right direction because they have identified their shortcomings and are rebuilding the system to be more user friendly.