Define good pet lol. I think all pets are good pets as long as there is an understanding of their behavior.
They are NOTHING like rats or guineas. While rats and guineas often enjoy their humans and need cage mates, hamsters generally don't become close to people and will often kill their cage mates (goldens anyway...some are more hostile than others.) There is always that rare hamster that thinks it is a rat and will snuggle with you. Most are great for observing and some handling but nothing more. They won't sit in your lap and shouldn't run freely.
Yes, they make lovely pets as long as you don't mind not seeing them dueing the day. But they don't live for very long, so make the most of them and handle them as much as you can to get a good bond. Well try anyway, some don't like being handled.
Depends on what you're looking for in a pet and the amount of work you put into them.
There's a few different types of hamsters that you have to consider before choosing one. There's the Syrian, which are larger but do tend to be more agressive and solitary. This isn't always true however. I had a teddy bear hamster for many years and played with it a lot and the only time it showed any agressive behaviors is if I woke it up. You have to be gentle and coaxing and befriend it just like every other small animal. Syrian hamsters are nocturnal so expect a fair bit of noise at night.
Dwarf hamsters are much smaller and often do well in pairs. I have mixed feelings about dwarfs. Right now I have a Russian dwarf and he is honestly one of the cutest things I have ever seen and is VERY friendly. He will sit on top of his home and stare up when he wants to be held, which is often. He's roly poly and small so you have to watch him...I like to sit him on my chest and have a hand under him in case he slips (compared to my degu's and gerbil he seems so clumsy) But my friend had a pair of dwarfs and they were mean. They'd sit in the palm of my hand and knaw on it, not just tasting either, they meant to cause harm. I think that was a question of lack of handling though. I find my hamster is a little of both, he's sometimes up at night, sometimes in the day. Then again he's elderly and is probably just tired a lot.
Finally the fastest but least handalable type of hamster is the roborvski hamster, or robo hamster. They don't recommend handling them because they are tiny, fragile and have poor eyesight..Often running right off an edge of a table because they thought it continued on. But they're super entertaining to watch and love racing in their balls. It is suggested you get pairs for this sort of hamster. These hamsters are NOT nocturnal, they are..Dirunal I think it's called (excuse my spelling) which means they are most active at sunrise and sunset.
In short, yes hamsters can be very good pets, but it depends on the time and love you put into them as well as what you are wanting for a pet. If you want a pet that's easier to handle and quicker to trust...I would suggest going with a gerbil. They're usually very sweet, rarely bite and are incredibly curious about things.