CiviCRM has acquired a reputation in some quarters for being tricky to install and to run on the slow side. This is all relative: the code can reliably handle millions of records - and the CiviMail component can handle bulk mailings on that scale too. Of course this high end use requires a high end server, but for organizations with up to thousands of contacts records who want a constituent relationship management system that can also provide membership, contribution and mailing and a forthcoming events management module, performance is more than adequate on a reasonably well resourced shared hosting environment. As for installation, the wiki documentation has improved considerably, the support on the mailing list is great, and installation is straightforward if you follow the instructions. If your web host just doesn't support it, urge them to or find another host - it's worth it!
It's true, CiviCRM takes some commitment to understand its power and features. But for what it can do to empower non-profits with true Web 2.0 sites, in my opinion it has no rival. Moreover, the project is under very active development, so refinements and improvements and support for new versions of the underlying CMS come in a reliable stream.
In addition to the available demos at demo.civicrm.org, there are specialist web hosting services such as www.opensocialsites.com that are designed to support CiviCRM and will even install it for you if you are a serious non-profit organization.