Daughter's boyfriend asked me just last week. I said 'yes' (of course) as they have been going out for 7 years (and I'm sure would ignore me anyway if I had said 'no'). Whilst he is not the ultimate 'catch' and is unlikely to ever be a high earner they clearly love each other and should hopefully be able to make each other happy.
I know from bitter experience that parents really should not make negative comments about their children's choice of partner (unless they are really 'dangerous' such as violent or a druggie - and even then, trying to steer them away is a tricky prospect).
My parents didn't like my girlfriend (now wife of 25 years) and made it pretty obvious when we were first going out and then got engaged - the context being that she is not as academic/educated as me and pretty outspoken. Phrases like 'you could do better than...' and 'are you sure...?'. Bottom line is that they ended up damaging their relationship with myself and my wife (and now their grandkids) - not to the point that we don't speak or see them or anything, but just that we don't make a big effort to spend time with then as it is awkward.