DSE is a server or servlet, so it does not provide any user interface services per se. You'll have to look beyond DSE itself for assistance with UI development. What DSE/Solr does provide is a clean and simple HTTP web service that your application layer can call with standard HTTP interface packages, such as SolrJ that comes with Solr. There are Solr interfaces available in other languages as well, including python, but that's outside the scope of DSE per se.
Solritas or Velocity Reponse Writer as it is now called is a nice, cute demo in standard Solr, but it is highly recommended that production apps do NOT use it or similar techniques for interfacing with Solr. Generally, DSE/Solr will run behind a firewall where it is not accessible by end users in a web browser, which is what VRW does. So, although VRW can be used for internal demos, it is not a solid basis for production apps.
Generally, DSE applications will have a three-tier structure: 1) DSE/Solr, 2) an application layer, and 3) client/UI code that runs in a browser.
Your application layer (maybe in Java or even ruby) will talk to Solr over HTTP. Your client/UI code will talk to your app layer, probably also with an HTTP-based REST API, but that's up to you.
I don't personally know enough about Blacklight to know whether it will meet your needs or not. But, if it runs as a standalone app and talks the Solr API, it may be worth a try.
And, of course, you can run the DSE Wikipedia demo, as shown in the DSE doc. But, as mentioned, it is not a recommended approach to application architecture. It's more to demo the search capabilities of DSE/Solr itself.