Following up to the previous posts regarding the elusive nature of defining what exactly is meant by failure, and considering it is literally July 1st, some thoughts on the opening day of the battle:
The accepted narrative of the Federal performance on the 1st day is that they succeeded in stopping the Confederates from obtaining the crucial high ground sound of town.
It involved considerable destruction of two corps which were out-flanked by Confederates coming down roads that approached from directions where they were known to be located, and the death of a corps commander and acting wing commander while he was doing the job of a regimental commander.
They failed to keep the crossroads in town or to prevent the separated Confederate forces from reuniting.
The position that was retained was good defensive ground, but the initiative passed entirely to the Confederates for the remainder of the battle because it proved to be poor ground to launch an offensive from. Although the names of the hills have become legendary, there really isn't any reason why they had to be held, the Pipe-Creek line that Meade initially wanted to hold would have served equally well, and perhaps better, as a defensive position.
There is no evidence that Meade intended to hold the high ground south of town, he said in his own words that he wanted to defeat the Confederate army in detail while it was widely scattered. Thus, Reynolds must have been acting with the goal of holding the crossroads. They not only failed to do that, but got destroyed in detail themselves. I think the performance of the high-command of the Union army on July 1st was a total failure that history has glossed over simply because they won the battle. It illustrates the difficulty in deciding such things, you benefit from hind-sight and whether or not something was a success or failure is entirely a matter of what perspective you view it in.