I've been noticing a proliferation of vanity URLs in place of the awkward polynumeric and totally anonymous URLs G+ is assigning to its users. The vanity URLs look like
I personally would love to see G+ allow vanity URLs, but in the meantime, going with a third party shortening service may cause you problems down the road, and may in fact hinder search results for your profile (it's an SEO thing). There's also the potential for a vanity URL company to stop supporting the link. And I've heard of some shortened URLs leading to the wrong profiles.
If you just want shorten your G+ URL, then Google owns its own URL shortener (http://goo.gl/). What you get is no less anonymous than the polynumeric one, but it's definitely less cumbersome. For example, my assigned G+ URL is:
but goo.gl shortened it to:
For a more technical explanation,check out this post from Cirruslabs.