WP should be very easy to maintain if your designer does a good job. Make sure you find out if your designer's will check that their work will "validate" which means that they've tested all of their code to make sure that all browsers will read it properly adn there will be no bugs that cause you problems in the future.
The Wordpress interface is easy to use once you're logged in. If you want to add a post, you just go to the add a new post section, write it, and press publish. The only thing that can be a little tricky is formatting images in your posts - like if you wanted to present a 4 X 4 square of pictures perfectly ligned up in your post that can be a challenge... but if you're just sticking in one picture at a time it's no problem at all.
There will be a learning curve to figure out the lingo of websites... but there are TONS of resources for wordpress websites. All you have to do is google your problem and you should find plenty of advice.
Also, make sure you know exactly what you want from your website. Wordpress sites are really easy to tweak if you know what you're doing, but if you're not interested in learning HTML and PHP, or how to install your own plugins etc. you might have to pay someone again to modify your site if the original doesn't work out.
Hope that helps!
Here's my new Wordpress website hosted with hostgator . I built it myself if you're interested in taking a look:
http://daintychain.com
