Umbraco is a bit different than other CMSs like Sitefinity, DNN, or Drupal. It does compare well to Sitecore.
Yes, there is a bit of a learning curve. I think the XSLT can cause that, but more likely its just the fact that you have to understand how Umbraco is structured. There are very few "modules" out of the box that you have to arrange and style. Rather, it allows you to easily create your own structure and markup that doesn't force you into a box that is hard to get out of.
I've used Drupal, Sitefinity, WordPress, Sitecore, and some others and frankly Umbraco is my favorite. If you know how to develop great web sites and you don't want limits on your design, markup, or client experience then Umbraco is a great choice. If you aren't really building a site but just want to put pieces together and get "something" working, then it may not be worth your time. If you build lots of sites or want your end users to edit content easily (not just a big rich text editor), then it may be worth overcoming the learning curve.
The videos are totally worth the $20 to watch BTW. They are far better than any documentation you can find and after maybe 5-6 videos you should be "getting it". Just buy one month and cancel after that.
The community is awesome too. If you're struggling, head over to the http://our.umbraco.org forums and get some help. There's lots of it over there.
Also, try installing the Creative Web Starter Kit package or the Blog 4 Umbraco package to get a head start. Those will be more familiar to those coming from a Sitefinity or Drupal background and may help the learning curve flatten out.
Good luck!