For an editor like me, I see the purpose of press releases as a way of imparting information that a company deems important. Companies usually see it this way, as well.
Sometimes, however, the press release is a way to puff up the firm, unhappily. Unhappily, because it wastes the time of everyone -- the people putting together the press release, the people approving it, the people distributing it, and the people reading it.
In this case, I do like to examine the complimentary quotes, because they cast light on how justifiable the puffing-up is. Here is an example of how to read between the lines:
A press release I received recently announced a "strategic alliance" between two companies. Now, a siren should go off when you read the phrase "strategic alliance," because it usually means "another, larger company finally noticed us!"
Next thing to look for: the quotes from the principals involved. Read the quote by the company issuing the press release, and then compare its wording with the quote from the bigger company. The amusing (to me) part is when the bigger company does not even name its apparent strategic partner!
Or, the bigger company might acknowledgee the existence of the first, but not quite in the way that the first company might expect. Words to this effect:
Collaborating with a market leader like [firm #1] will further accelerate how our software users create rich engaging products.
Notice the use of the word "a" and "like", as in "a market leader like" -- a meaningless phrase designed to appease the new strategic partner without insulting all its other strategic partners.