Strong competitor for your coin
I bought a set of 4 of these for a home quadrophonic production/composition studio. I needed a proper monitor setup as I'd lost access to the university based studios that I'd been using, and my home studio was comprised of nothing more than a decent quality stereo setup and a mediocre quality surround setup. I briefly considered Adams and Genelecs as that was what I was using in the studios I'd had access to, but given my budget and my need for a set of 4, those were not going to be an option. Instead, I ended up checking out the Mackie HR624s & MR5s, KRK Rokit 5s & 6s (okay...), Tannoy Reveals (501a & 601a), and a bunch of the other usual suspects (Behringer, M-Audio, Samson, etc... mostly crap), all of which are active monitors. Based on price and performance, it came down to the MR5s, Rokit 6s, or the Reveals... until I found out Tannoy offered the 601P, a passive version of the Reveals at an very reasonable price. This allowed me to use my existing amps and save several hundred dollars rather buying a set of active monitors.
Having been spoiled by Adams and Genelecs, I was sure I'd be more disappointed with the 601Ps. In fact, they've proven to be very honest and (forgive the pun) revealing, without being harsh or fatiguing. The mid-range (300-5kHz) is full, present, and almost tangible, while the high end (5k+Hz) is clear and concise without being harsh. And while they claim a range down to 63Hz, as expected with a 6.5" driver lower end (40-100Hz) presence isn't as strong, though upper bass (150-300Hz) range is well controlled and responsive. Any lacking in the low end is easily fixed with the inclusion of a sub and I've found these Reveals match extremely well with my JBL PSW1000 with the crossover set around 100Hz.
I currently primarily compose electronic and computer music, but have plenty (years!) of experience tracking, mixing, and mastering pop, rock, gospel, classical, etc. To familiarize myself with the Reveals, I spent several days listening to recordings I knew well... my own and tracks from major label recordings. I was taken aback a bit by what I heard... the Reveals aren't entirely unforgiving, but sure they don't hide much. I was able to hear punches, pick noises, snare and bass drum rings, and vocal sibilances that I'd not heard (or at least noticed so obviously) on many other monitors (NS10Ms, JBL 4408s, KROKs, Events, Mackies, etc.) and speakers. Also, I found that they showed more bow noise, performer breathing, key clack, etc. in several classical instrument recordings. They also do a good job at portraying the differences between recordings made using different mics.
For my own purposes and setup they've been excellent, providing very good linearity and response. Their size works well for my quad setup, and with the front porting, they can be placed near walls with fewer issues. And in terms of budget, I can't think of anything else that would perform as well for even twice the price. Seriously... a comparable Genelec, Adams, or even Mackie setup would be $1000-$3500, so at $500 for the set of 4, I'm very very very happy with the purchase.
I can recommend the Reveal 601Ps in terms of performance quality and budget pricing. So if you've got a quality amp or two, or find a good deal on an nice Hafler or Adcom or whatever, then the 601Ps are a very competitive choice, and a heck of a speaker for the coin.