Short answer is "no". Long answer is still "no" (that should really be "not yet" rather than "no"). The application is still incomplete with a lot of work yet to be done. For example, the various 'bake' options available in 2.49 (and below) appears to be broken so, as of writing, it's not possible to bake normal, ambient occlusion and other 'baked' image maps, it's a bit too hit-n-miss right now, if you're lucky. 2.5's also got limited import/export capabilities right now in this early stage of testing so game developers and content creators are going to be well and truly stuck if switching now.
For a complete list of 'missing' features see this post on BlenderArtists.
The upside is that Blender itself is pretty 'solid' as an application and doesn't in-of-itself just crash. Having said that though, if you do hit problems it's unlikely that you'll be able to 'cheat' and fix or get around issues by loading the *.blend file into a previous version of the app either; Blender, like all software, tends to be 'backward compatible' only in loading old files into newer versions, not the other way around. In other words it's unlikely to be possible to load a new file into an older Blender just to bake an ambient occlusion or normal map of a model you've been building or improved in 2.5 (don't even ask about trying that with an animated model either!)
Bottom line is this: if you're already using Blender for production of any kind, stick with what you've got for now; certainly install (extract) 2.5 and poke around to get familiar with it, but don't try doing anything more than that else you could find yourself with some major, major headaches at this point in time (especially so with Blender Game Engine).
Having said all of that, and based on what I've seen so far, this may very well be the true 'making' of Blender in terms of what has always been that illusive 'Pro' uptake of the application.