I have to agree with Diafa and also Obama has his own points too.
I came to the US in 2007 and I've been here since then. I work in downtown Manhattan and live in NJ, just across the Hudson river.
On the streets, at work, on the subway, bus etc. I hear many languages, I see many different people in different - even traditional - clothing. No one cares about any race, color or any other stuff.
On the other hand, America is / may not be what people are dreaming of. No one will give you a job as soon as you land in JFK. You have to search for one, you have to speak English very well, you have to have some type of experience. Whatever you've done in your home country doesn't matter. They don't recognize. Even the universities abroad. If your resume doesn't show a US university, you're automatically second person on the list. US graduate, even from a crappy university, gets the job.
People are struggling for putting some type of US work experience. They take unpaid internships, attend seminars, go to courses and spend a fortune, just to have a resume that has a US school and some US companies as work experience.
I know many people with technical degrees like engineering, architecture, computers etc. They don't speak good English and they end up being a waiter at a restaurant, gas station attendant, busboy, loading / organizing coca cola refrigerator at a supermarket, mopping floors etc. They make around $8-9/hr before tax. Under the table, $8-9-10 max. Some of them complain, some of them are happy. They work at a cafe, eat for free, drink their coffee for free (Starbucks grande coffee is around $2.60 in NY) and make money for rent, utilities, transportation, cell phone etc.
As an engineer, you may have a better opportunity in your home country, however, if you can apply your engineering skills in an American company, you're the king.
There's also a point in a US immigrant's life, which I call "saturation point". You come fresh, look for a job, finally find something that pays $7/hr, then something better comes up, you switch jobs, now you're making $10/hr. You hold onto that for a while, meet new people, you start making friends, now you have people to go out and drink a beer or coffee after work. You start hanging out. Now, instead of eating $5 lunch from a street vendor that cooks rice and chicken, you start eating better stuff and spend $7-8 for lunch. You buy better groceries, you start going out with friends more often. Then you get a raise or get a $15/hr job. You say "what the hell" and go buy that nice sweater / jeans that you see the other day. You hear there are some nice malls around that have factory outlets etc. Guess what? They're too far and there's no public transportation. It has always been in your mind since you came to the US for the first time, you start looking at cars. You start saving and after some time, you go and buy a $3,000-5,000 car. Spend some bucks on initial maintenance. Now you have monthly car insurance to pay. If you're newly licensed in the US, it's always around $120-130 a month for a starter. Now you have insurance expenses, gas expenses, car wash, parking, you'll get some parking tickets ($65 in NY), you'll get some stupid violation tickets (cell phone - $130, blocking intersection - $160 etc). Your prepaid phone starts to kill you, what the hell, sign a contract. Now you commit yourself at least $60-70 a month for cell phone. You have a laptop, you want to use the internet at home. You start looking at cable service for home. that comes with TV too? let me buy that package, thank you. Now another $60 to $150 monthly cable TV bill (yes it's that expensive). Then with your new car and the places you hang out, you have a girlfriend. You start taking her to dinner, coffee, lunch, movies. Pick her up, drop her home. Tunnels, tolls, parking, valet, restaurant, tips, then her birthday, valentines day, anniversary, you have to engage now, go spend that $3000 to whatever your limit is on that diamond ring. etc. etc. the list goes on.
Basically, you come to a point that your lifestyle and expenses go up. You eventually eat better, dress better, go to better places, drive better cars etc. etc. and when these things "settle" and become regular for you, then you miss your home country. That's when you miss home and want to go back, because you eventually have everything you've wished for, a good salary, nice home, good furniture, electronics, car, girlfriend or wife and you can afford a good lifestyle. That's what I call "saturation point".
At this point, many, but too many people I know complain about the US and they say there's nothing better than your home country. They all regret coming here, they say everything in the US is bad, they would prefer making much less money but be with their family in their countries. However, none of these people go back. The ones that go back are always the ones who can't make it here financially. I've seen people who came here, set up a business,made a fortune and return to their country permanently at their 40s or 50s. I've also seen people who got tired of working like a dog for $7hr for years and finally said "f*ck that, I'm going back". But, nothing in the middle.
So, to summarize, it's a shot that you have to give a try. I wish everyone has a chance to come and see the US, see how things work here, if they can make it here and then decide. It's an important decision in your life, you have to make sure it's worth to leave everything behind.
Well, sorry for writing long. Again, good luck to everyone on the lottery.
At least that's my plan