I have used the us122 myself for as demanding a job as recording baby grand piano solos, and I found it to be an excellent unit for the price. The pramps are superior to the mAudios and far, far better than most internal soundcards.
There is no latency in recording due to the USB interface, and any latencies that might crop up can be adjusted for in the software. Additionally, the us122 - as with the majority of 2-channel audio USB devices - operated off of USB 1.1, not 2.0 (as to whether this is true for the new "L" model, I don't know). And, no this is not an issue. While FW may have wider bandwidth than USB 1.1 (BTW, it's actually narrower than USB 2.0), at the bandwidths (speeds) required for two channels of audio, this is not even close to being a problem. Some quick math:
USB 1.1 has a bandwidth of 12Mbit/sec. A single audio stream of 44.1kHz/24bit requires approximately 1.06Mbits/sec. This means that two channels of audio at that rate requires only 2.12Mbits/sec. This is only abut 18% of USB 1.1's theoretical capacity. One cound double the sample rate to 96kHz and still have almost two-thirds of USB 1.1s capacity left over for everything else on the bus.
When we recorded that grand piano, that was a 8-hour long session, not counting breaks. The Tascam shared the a laptop USB bus with a USB mouse and a 56x USB CD-R burner. Not once in that 8 hour period was there a single hiccup or delay, and the sound we got from the Tascam was much better than we got from the Mackie VLZ that we also had with us.
Take the reviews for what you think they're worth, but I have worked with both the comparable mAudio USB pre as well as several internal soundcards, and in my experience the us122 is the superior device, hands down, without even breaking a sweat, and it even beat the Mackie VLZ mixer for overall sound quality. FWIW, YMMV and all that.
G.