+1 on not being able to use a phone while on dial-up (without a second line.) Indeed, I had more than one internet session interrupted when someone picked up the phone to call someone. (On the plus side, that's when we got a second line. It now comes into the house as part of the same physical wire that our first line uses, but it's its own thing. And it comes in handy to have another dialing landline. Yes, we still have landlines where we are; in a power outage, a landline will work so long as the phone line connects, as it gets its power from the line and not the house. Cell towers have gone down in outages around here, but the phone line's been rather consistent.)
You could also tell by the squawking and beeps if you were connected or not - it had a "song" to it, and if it kept going too long you knew you were having Issues.
We used MSN and NetZero, incidentally. AOL send out free disks (and, later, CDs) in just about everything they could stick a disk in - junk mail, cereal boxes IIRC, etc. - but they were always a little out of synch with the rest of the Internet and were kinda a trap for people who didn't take the time to figure out what they were doing.
By 1999, I believe most modems were 56K, which is nothing compared to broadband but it did the job... if sometimes slowly (particularly when lots of graphics were involved. Videos? Be willing to wait forever. Forget movies.)
As for ugly websites... remember the (perpetual) "Under Construction" GIFs?