I have my own personal reasons to dislike them, but I'd be interested in knowing some of the key reasons for their almost universal hate in the tech world.
They have a history of confiscating domains on behalf of authorities without a court order or other legal reason. They helped author SOPA, written into drafts of the bill as the registrar to receive confiscated domains, the same way they already are for ICE/DHS. Registering your domain through them is a completely unnecessary risk to one of your business's most valuable assets. No moral or ethical stance about their former CEO, their "hot girls" advertising, or their upsell tactics is necessary to pass them over.
Because you can not get anything done without them trying to up-sell you services that you do NOT need, they use some questionable tactics. You have to Opt out of services you don't need, it goes page after page. Safe yourself the headache go with NameCheap.com or some other respectable company.
There are several users who've posted horror stories of how they accidentally deleted their domain when trying to disable autorenew as a result of godaddy's misleading UI, who were then told that the domain name had already been auctioned off upon contacting godaddy about the mistake (keep in mind this was during a time frame for which they had already paid for the domain name, not after expiration)
I have my own personal moral reasons for not wanting to support them financially, but I also find that from a technical standpoint their shared hosting and domain management is terrible. I find the control panels extremely confusing, and the few times I have had to host WordPress sites with them they were slow as molasses in January.
They've always been a questionable company. Compassionless customer service (unless you're buying something), the fact they are always trying to up-sell you and the biggest of all: the fact they were massive supporters of SOPA.
The one time I made the mistake of buying something from them -- a domain-name evaluation -- they treated me like a patsy. I feel like I lose brain cells every time I come anywhere near their site or their ads.
They were a big supporter of the SOPA legislation, for one.
This is why I don't. If you don't support an open internet I don't support you. I'm also not crazy about the hunting elephants thing.
The evening I heard about the elephant killing, I moved all my domains from GoDaddy and swore them off forever. By the time SOPA happened, they were already dead to me.