I haven't jumped on the Bluray bandwagon yet myself, but since my DVD player seems to be on the fritz, I may be doing so sometime soon-ish.
It's true that the picture quality of Bluray discs isn't going to vary hugely from player to player, because as long as they output the digital signal correctly, it'll be pretty much the same thing regardless. What you see will depend more on the kind of display you're using than anything else.
However, you must not take this to mean that all players are created equal. The quality of the de-interlacing and scaling can vary greatly, and many units will certainly cheap out on this aspect, giving subpar results. For someone who still primarily wants to watch DVD's without having to buy everything over again, this becomes tremendously important. De-interlacing in particular is critical, because accurately recovering the original frames without combing artefacts and other intrusive errors entering the image will have a major effect on what is seen.
In addition, there is the issue of compatibility to consider. Though it may be less of an issue now, you should still be prepared to update the firmware of your Bluray player to accommodate the ever-changing copy protection schemes: failure to do so may result in some discs being unplayable, and this will also depend on whether the manufacturer keeps up with current releases in a timely fashion or not. Some discs are notoriously slow to load, often due to overly-complicated menus and such, and players that have longer boot-up times to begin with will be particularly sluggish when playing these titles.
It is without doubt that Bluray is a more problematic and difficult format than DVD, being rather less user-friendly and requiring more effort to get things the way they should be. The benefits of high definition make it worthwhile, but you must be prepared to deal with these kinds of issues. Because of them, choosing the right player is a task worthy of giving thought to.
If you can afford it, I definitely recommend getting an Oppo player, because the company's support for their products is fantastic and you'll get top of the line performance for a fraction of the price from any other high end manufacturer. Otherwise, the PS3 is widely respected for its Bluray capabilities and will give better results than many standalone players out there.