This is my first smartphone and I have to say - it's an incredible piece of technology. I've always been a big fan of Samsung products as they have always stood the test of time. My previous phone, the Tocco Ultra, had an awfully insensitive touch screen and I have to say, using the Galaxy Ace's screen is an absolute dream. Ideally I would've liked an iPhone but unfortunately, being a student, that just makes it financially unavailable to me so I looked for an equivalent on a lower budget. I've used my friends iPhones quite a bit and have to say this stands up for itself way more than I anticipated. Your every day usage for things like youtube, music, videos, texting, the odd phone call are rapid to interact with, there are a huge number of apps available in the market and I would go as far as saying its wifi capabilities are incredible. If it can find a free wifi signal it'll just connect instantly if it's turned on - totally hassle free! The facebook app is great and constantly gets updated - something a lot of the apps can boast. Technology gets older and older faster and faster these days, so to have an active app market constantly keeping us on our toes is amazing.
The only drawback I find is flash support. The processor isn't quite powerful enough to run flash, apparently, but it runs all the games available just fine - surely there must be something that can be done on this front by the developers! Maybe in time. The iPhone still doesn't have flash support so I guess you aren't missing out on anything really. I hope this gives a better insight into choosing the phone as I honestly would recommend it to anybody wanting high quality for reasonable price. :)