I really like Adobe Lightroom. I like the interface, I like the library management, I also very much like the RAW handling. The program has a fantastic noise reduction system that competes very well with Noise Ninja. And perhaps the most important benefit of Lightroom is that it melds functions that previously required Adobe Bridge and Photoshop. It is definitely my RAW manager of choice.
That being said, there are a few things that annoy the ever-loving crap out of me.
One: there are functions that are only available in "library" or "develop" mode, and no way to access them without switching back and forth.
Two: while the program runs smoothly on a multi-core CPU, it runs like absolute garbage on a single-core system. I'm not talking a slow system, either. 2GB of RAM, 128MB ATI Radeon, and a 3.2Ghz AMD CPU. Yet it takes a whole minute to export an image, and simply moving through the library maxes the CPU at 100%. The program isn't terribly memory efficient, but it's an outright bloated mess in regards to the processor.
Three: And about that memory usage, considering all of the stripped functionality of Photoshop, you'd expect Lightroom to be easier on memory. It's not. You can easily run into the 300MB+ range in active memory just sitting there, and I've hit nearly half a gig with small files. Apparently, the developers at Adobe are clinically incapable of writing memory efficient applications.
Five: The price is a bit high, as with seemingly all Adobe products. Photoshop is $700, even the stripped-down Photoshop Elements is $100. At $300, it's in line with DxO Elite, but double DxO Standard. It's also $100 more than Apple's Aperture and Bibble Pro. The only program that out-prices Adobe is Phase One's Capture One, which is intended for tethered studio photography.
Four: And finally, removing chromatic aberrations. You know the kind. The purple or red fringing around highlight areas. Well, Lightroom is retarded when it comes to these. As in, it doesn't do ANYTHING to them. You may as well not even have the feature. Lightroom is SO terrible at it, that if the rest of the program wasn't so good, I would have ditched it.
UPDATE: I forgot to post a good comparison of the major converters from Twin Pixel.
I also wanted to mention that, on that same single-core system I've used Bibble and Capture One. Capture One is better at handling a 150MB, 65Mp RAW file from a Phase One 65+ medium format back than Lightroom is at handling a 15MB RAW from a Panasonic GF1. When working on a particular area of the image, it's very fast.
Capture One maxes my CPU, but it never dominates it. Where Lightroom's interface will freeze when it's doing stuff, Capture One maintains UI integrity. Buttons still operate, I can manipulate the program, I can switch from image to image, etc. Bibble is a similar story. Everything still functions.
And as a final note, it's perhaps not the fact that I'm running a single-core system, but Lightroom itself. I just found this thread at Adobe's message board, with over 1,000 replies, of people complaining that Lightroom 3 is slow.