We are an unschooling family and it's without doubt the best thing we've ever done.
Unschooling (or any other form of home ed) isn't in any way a lazy or easy option. Unschooling is not unparenting, children are not neglected or left to bring themselves up. They are encouraged to follow their interests and passions, and parents put a great amount of effort into facilitating that. Parenting an unschooled child is an incredibly involved process, not a way for parents to get more free time.
I don't believe that unschooling causes children to be unmotivated or unable to cope in 'real life'. I know a lot of children who went to school and are completely unmotivated and unable to cope in real life! Unschooling doesn't need to prepare children for real life, because unschooling IS real life, it's living and learning through everyday experiences, rather than the artificial environment of a classroom. My children are involved in every part of our life, from helping run the household to cooking to travelling on public transport to booking a holiday to managing money. I daresay they have more life skills than many children who go to school! Because they are able to help make decisions and because their opinions are valued equally within our household, they are confident and self motivated, with good self esteem.
Unschooled children are not unable to meet deadlines or follow rules. School is not the only area of life where good timekeeping is required. Taking a bus or train journey, getting to a club or hobby or event on time, baking a cake - all of these things require good time management. Unschooled children can see the real life benefits to good time keeping (get up in time to catch your bus or you'll miss your club, keep an eye on how long your cake has been in the oven or else it'll burn) and so will naturally learn these skills. An unschooled child isn't sheltered from the reality of the world, we ALL have rules and boundaries we have to comply by, obeying the law, following instructions at a club we choose to join, social etiquette etc, so it is daft to suggest that unschooled children will never be able to fit into society just because they don't go to school.
Allowing your child to follow their interests 'to the detriment of all else' is not a bad thing. I can't think of a single hobby or interest someone could follow which doesn't encompass a multitude of 'subjects' and use a vast range of learning skills. Almost everything we do in life involves some level of maths and english, for example. I have never known a child who is only interested in one thing, where that thing is limited and where there are no opportunities for that interest to lead onto other interests - on the contrary, being allowed to follow your passions and your own curiosity will naturally lead from one topic to another, and because an unschooled child can spend as much time on a topic as they like, and delve as deep into it as they like, they will usually have a much more in depth and comprehensive view of it than they would had they learned it in school.
I think it's important that children are encouraged to follow their passion, whether in school or otherwise. I don't think that it gives children false hope or sets them up to fail in the real world, quite the opposite. No, not everyone will waltz into their dream job, often you may work several jobs you don't like whilst you aim towards whatever you're passionate about, but unschooled children are no exception from that - like any other child, they may do part time work whilst studying at college or uni. I don't think unschooling gives kids unrealistic expectations of what they can achieve in the future, but it does give them the self confidence and self motivation to strive for something they want to do. The idea that an unschooled child would only thrive if they were self employed or that they only fit a certain niche in the job market is a daft one.
Studies show that, unsurprisingly, children learn best when they're genuinely interested in whatever they're learning about, and learning about it in a way which interests them, as opposed to school where you're often taught boring things in a boring way purely for the purpose of passing a test. Human beings are innately inquisitive, we have a natural desire for information and to learn new things, especially as children. It would be nigh on impossible to stop a child from learning. Things like 'just' playing or 'just' watching tv are incredibly educational. Being able to learn something because you have a genuine interest in it, rather than because you're told you have to learn it, means the information is more likely to be retained long term, rather than retained for as long as it takes to pass an exam and then forgotten again.
Not all children will have a good unschooling experience, i'm sure there are some children who have been unschooled and haven't come out of that experience well, but I would suggest the same is true tenfold for children in school. If a home educated or unschooled child doesn't do well in life or is a bit 'odd', people always seem to put that down to the fact the child was home educated/unschooled, yet plenty of children who go to school don't do well or are a bit 'odd' and no-one ever puts that down to the fact that they went to school! My hopes for my children are that they are happy, that they have good self esteem, that they feel confident and able to make decisions and to problem solve, that they are self motivated and that they have a natural thirst and passion and joy for whatever they do, and unschooling is helping us to achieve that.