I like how they are always trying to make their work more interesting for my clients, which is great because it makes me look good too! The fact that you can use them as an email marketing tool with all of your contacts in one place has been very helpful (and free). They don't have any fancy bells or whistles yet but when we do get those things implemented there will be no stopping us from using our new tools every month!! We've used several other services over time including MailChimp/Aweber etc., so this isn’t really anything unique about these guys - just another option out there if needed :).