It's easy, it works well for SEO purposes - I've seen some really great results from just using this! My only real dislike would be that you have limited options in terms of design/layout (but then again there are loads more plugins out now).
We're seeing lots success with our internal sites at present but we still need external ones too so having something like jelly url has been fantastic as its helped us get those going quickly without needing any coding or technical knowledge etc., which was always an issue when working through other providers before!! And best thing about jelley? Its quick and simple :) Highly recommend if your looking into getting one set-up rather than waiting until someone else gets round doing all their own work first ;) Our main benefit currently though is being able to easily redirect users directly back onto my site once they click away after visiting via another website i'm linking to within content such as social media posts / articles etc..