Since this is to be a first snake I'll try and use that as a perspective in terms of cals. My thoughts on Cals is that they make a great 2nd or 3rd snake once someone has some snake experience under their belt, but I am hesitant to recommend them as a first. First the pros- Cal kings are very hardy and reasonably forgiving of temporary husbandry mistakes. They are very attractive and are straight forward in their breeding if breeding is of interest to you. They are voracious feeders once they are started on pinkies as hatchlings. Most settle down and are handleable after about a year in age with regular handling. They are a very managable size and will never reach a problematic size. They are common and generally inexpensive so if it doesn't work out you are not out much $ and there is usually someone willing to take it off your hands. And they are often active during the day and will move around the cage as opposed to laying in a coil in one spot for days on end (however keep in mind they are looking for a way out, more on that below)
Now the cons- Young cals and snakes that have not been handled do not handle well. They thrash and musk and will at times bite. Most will calm down over time with work but some do not. I have 2 kings, my male is one of the most calm and handleable snakes I've ever had. He will even come up and gently take a rat out of my hand for feeding. My female on the other hand will still coil and rattle when the cage is opened and will still thrash and musk with handling. She will even take a hunk out of my thumb more often than I can count when handled although her biting is more feeding in nature than defensiveness or aggression. She is 5 years old and last summer I made a determined effort to tame her and handled her every single day for over 6 months. I got her so she USUALLY did not bite or musk but she was always unpredictable. Most kings fall in somewhere between these two.
Another con of kings is they are escape artists. They will spend their waking hours constantly looking for a way out. If there is an opening they will find it and once they are out they will be gone. They can move very fast when they want and even if they look like they are just leisurely slithering along they can bolt and be gone in seconds. Also, kings can not be caged with other snakes as they will eat each other.
For a 1st time snake I would encourage you to also research cornsnakes and captive bred - repeat captive bred (not wild caught or captive hatched/farm raised) ball pythons or possibly rosey boas. They have many of the same advantages but are not as prone to thrashing/musking/biting as hatchling kings. that's my $0.2, hope it helps. Not trying to turn you off to kings, there are many reasons they are so popular but I think there are other snakes that deserve consideration as a first.