There is a learning curve with LR.... it's worth buying one or more of the books about it, to get the best out of it.
LR is designed for high volume work... If you shoot a lot of pics and need to turn them around fast, it's the right tool for the job. It also is a powerful cataloging tool. I don't have experience with Aperture, but would imagine it's similar. I have used a few other similar programs in the past, worked with Adobe Bridge for a while, but now use LR3.
LR doesn't replace Photoshop for me, the two compliment each other. Recently upgraded to LR3 and CS5 and they both have some nice improvements. Found a number of glitches in LR3, but just downloaded 3.3 release candidate, which appears to address some of them.
IMO a trial of these softwares is really not enough to evaluate well unless you have used an earlier version.
I shoot 1000 to 2000 images some days and use LR to catalog, sort, lightly edit and make thumbnails from the keepers. I'd recommend it for anyone with 100s or 1000s of images that they need to handle quickly and efficiently. My biggest project this year was a two day shoot with four photographers and I had 12,000 RAW images to work through afterward!
I use Photoshop or DPP for more complete and final processing of individual images, into larger prints or digital files, as needed. Beginning with CS5 and LR3 I'm using DPP less. I used to use it for better handling of high ISO images than I was getting with LR2 and CS4... but the newer Adobe sortwares are doing a much better job with high ISO images, so I find much less need for DPP. Still, there are some things it can do, so I keep installed and up to date. I have two copies of LR3... one on a laptop, the other on a desktop. I only have Photoshop installed on the desktop, since I don't like to use a laptop for precise image editing (a laptop's screen really isn't up to it, impossible to calibrate very well due to viewing angles and highly variable ambient light situations). I have DPP installed on both laptop and desktop, just in case.