It's really hard to time the market. With all the new construction around LA Live, prices should probably go up compared to the rest of LA. But many people say prices in LA will continue to go down for the next couple of years and prices already reflect the future improvments of the neighborhood.
Try to find out the atmosphere of the building. Some buildings have roof top parties, while others are like retirement homes. Someone selling/renting you the property will won't really tell you.
Street noise can be an issue downtown. Trash pick up, bus service, windows close to common areas... Some buildings have double pained or triple pained windows which help.
In a new building HOA is just and estimate. It could go up or down. Eleven acutally went down.
Currently don't buy presale. Developers are usually lowering the price around 15% a few months after.
Visit the area at night.

Below is a map of what I think are good (green) and not so good (black) areas at night.
This is just my opinion, go to the area yourself if you wanted updated/real info.