You can get Lightroom to import all the folders containing the pictures you have been using in DPP but none of your edits will be saved in Lightroom.
On "import" all LR does is make a file of the location of all your images - a catalogue - but the images and their location does not change.
For me one of the best features of LR is it's indexing and keyword function, if you have tens of thousands of images the ability to search by keyword or EXIF data is invaluable.
I recently moved from DPP 3.X to LR 4 and now LR 5 and I much prefer the workflow in LR. Having said that I recently downloaded DPP 5.0 and was quite impressed with the image quality improvements, but DPP 5.0 only works with I think the the most recent Canon full frame cameras (I would still need DPP 3.x for my 7D images which is royal PITA).
You can download a trial of LR and there are loads of free videos tutorials on the Adobe website.
HTH
David