I have to say that of all the TFT monitors I've used or evaluated recently (Iiyama E431S, Samsung 172X, Samsung 172T etc), this in my opinion, is the best all round 17" TFT.
Stunning build quality (aluminium) - the fit, finish and design is definitely a notch above the other monitors in the same class. No bendy plastic in sight. It screams quality and attention to detail - everything from the screw in stand, multiple connectors, to multicolour graphical OSD, diagnostic testing upon power up. Comes with no less than 9 different sets of cables!
Picture quality is generally comparable to the best of the rest in the 17" TFT range (Iiyama E431S, Samsung 172X etc), and it has the legendary 20ms Hydis panel (which if you believe Toms Hardware Guide, outperforms the Samsung 12ms, AUO 16ms, and LG/Phillips 16ms panels in fast motion games).
Two minor gripes - the blue led on the front panel is too bright (cured by sticking a small circular post-it note on it) and it is sensitive to cheap DVI cables. (It does come with good quality shielded DVI cable but I initially used an el-cheapo cable from my old PC to save time and it resulted a tiny red dots running up and down the left and right borders of the screen.)
A slightly bigger gripe concerns contrast ratios. The stated specs show contrast ratio specs to be similar to other high end panels, but in use, I'm not convinced that the contrast ratios are as good as they could be. In games and DVDs, you have to fiddle with the gamma / brightness settings otherwise you miss out on some of the details in dark or shadowy areas. When you do this with some films (.avi, .mpeg, DVD etc), it sometimes oversaturates the rest of the picture.
If you compare this issue to the Iyama E431S, the difference is particuarly stark - the E431S is superior in bringing out detail in dark areas of the screen without you having to fiddle with gamma or contrast settings (if you watch a B&W film like The Third Man where people run around through shadows, on the Iiyama E431S, you'll know what I mean.)
Generally though, using a fixed contrast ratio on the Acer across a variety of applications (in order words not changing the settings to suit the particular application - internet, games, DVDs etc) is generally good. A contrast ratio on the E431S for example, which may look good when playing DVDs will burn your eyeballs when using something like MS Word.
However, I don't want to end review on a negative point because the AL1731M is the best 'all round' TFT monitor that I have used (others were Iiyama E431S, Samsung 172X, Dell 1701FP, and a couple of older Samsungs). The Acer just tends to be far more 'even' in its all round abilities. I'm suprised that this monitor hasn't got more publicity because it is an excellent all round monitor.