Fast inserts, queries way faster than in SQL Server.
Certain research which was unattainable beforehand, now is in reach.
Some GUI Tools out of the box, better python integration. I would love to see some nice query engine, tooled specifically to Vertica extensions of SQL (with IntelliSense). We currently use TOAD, but it has a lot of bugs and does not provide full support of all Vertica features. For example with the "copy to" command it is buggy - extremely hard to debug.
Other issues would be better query plan display and better management tools like command line admin tools. (MC would probably solve a bit here, I saw a demo on the conference). We have several avid Python users in the company, but this how maybe lower priority after I reviewed my conference materials and found that Vertica now has native Python driver.
I was acting as my own DBA for a while, so a lot of hurdles before. But things are getting easier as more people in the company bought into the solution. I also got HP Training in house. (Thanks Herb!)
We can scale a lot, wish it was a bit more affordable.
It complements our SQL Server solution.
Switch to per node from per TB.