Had 'em for well over 20 years.
CONS
If you want a dog to let off the lead and play fetch - not for you.
If you want a dog to run miles a day with - again no (look at spaniels).
If you want a smart dog - again no. Bless.
Also mine (an old man now) costs £150/month insurance. But he is old and it's reliable insurance. I'm guessing a smaller mongrel may be cheaper.
PROS
If you want a dog that is less challenging allergy wise - for me they're great. Regular dogs set me off, but not greyhounds.
If you want a 30kg lap dog - great.
If you want a dog who won't give you stick if the weather is crap and you just want to take them for a very short walk until they've dumped - they're marvellous.
If you want a dog who primarily sleeps - ✔️
If you don't want to groom - fabulous. But you DO need to clean their teeth.
If you do decide to get one, ask around for a good rehoming organisation. The dogs should be de-fleaed, wormed, neutered before you get them; the org should stipulate that the dog goes back to them if you can't keep it for whatever reason; they should give you a frank assessment of their dogs' personalities and traits and how your home lines up with them; and should provide a few weeks' pet insurance when you adopt, so the dog is covered from the get go.
I took most of mine to a local dog training class, as much to get them used to other breeds of dog as anything.
Dogs straight from kennels will not have met various bits of a home environment - e.g. most likely any food they've seen being cooked would have been for THEM - still a lot easier settling in a new ex racer than a puppy though!
HTH