Second time here for me but the first time for my fiancé and he absolutely loved it. I visited 10 years ago and it has changed quite a bit, not necessarily for the better either, I still really enjoyed it though.
Positives: It is a magical and iconic place. Although it is very busy, we never felt unsafe. The lights from the billboards are always incredible and the place is filled with places to eat and drink, however, the establishments here are, as you would expect, pricey. There is always something to see or do here, including the iconic red steps, where, if you can get on them, you can watch the diverse world go by. There are street performers which are good to watch, be aware though, their main aim is obviously to get money out of you, so keep them at arms length if you're on a budget! We even saw The Naked Cowboy on one day we were there. Also saw filming of a 50's film taking place with lots of 50's cars lined up, this was nice to see. The theatre district is here too (Broadway) and there are many amazing shows to see if that is your thing.
Negatives: Far too many gift shops! Super, super busy, to the extent where you come to a standstill sometimes. If you don't like crowds, this is NOT the place for you. The smell of weed from every single street was overwhelming sometimes, this was not pleasant. People selling bus tours are everywhere, thrusting tour leaflets in your face, some are more polite than others. Beware of the scammers, we came across ones posing as musicians "trying to make it". They will autograph what appears to be a CD in return for a fee, there is no CD, it's just a piece of printed card. It's hard to get by them because they will try and get you to stop and almost block your right of way. The centre of Times Square is filled with "photographers" who will take your photo without your knowledge and then try and get you to part with your money for a copy of the photo. You need to be quite forceful with all of these people, politely dismiss them and keep walking!
Times Square is not everybody's cup of tea, but you need to visit it when in NYC, even just to say you've been there.