I think it a phenomenal option for small to medium sized businesses. The support that we received was also critical to our success after implementation. I was not able to renew with Sugar since I moved on to another role in a different organization, but I recommended to my friend that her company try it out, and they are still a user to this day.
I'm no expert, but I don't think sugar is a good fit for every organization - I've not seen too many people engage from an enterprise level. Know what your end goal is in CRM implementation and be patient. Treat marketing as a sales enablement tool and CRM can prove extremely successful to you.