I bought my IFly for a trip west this past July and I am generally pleased, although the screen would be better if it were a bit more visible in bright light. It works of course, but takes some getting used to. I am an IFR-rated pilot (Commercial ticket) who flies VFR about 90% of the time (I put the IFly700 in my Aviat A1-B Husky), but I have used the IFly in both IMC and VMC. Obviously I do not use the IFly for primary navigation in IMC (I have an IFR-certified Garmin 430W for that, and I use a Garmin 496 for weather, "slaved" to the 430 to show the course line from the 430W Flight Plan). I use the IFly primarily for the charts, whether IMC or VMC, and for situational awareness in both. I have the full chart subscription, and find the approach plates and the Low Enroute charts very useful, and I especially find it useful that I can easily toggle between the Sectionals and the LE charts when flying in IMC. Avoiding fumbling around with approach plates is another good reason to have them in the IFly
I particularly like that the IFly shows my course on the actual chart (would the course overlay be useful on approach plates? I don't know, but the answer is "maybe." My 430 shows position on the approach, so it would just be an additional cross-check to have the IFly do that. Because I mostly fly GPS "direct" rather than using airways, I find that in IMC putting the Sectional on the IFly is especially valuable for good situational awareness. The IFly is legal for using as the only source for chart info (actually there is no legal requirement to even fly with charts, specifically, although one would be hard-pressed to claim that one was fully prepared for the flight without current charts, should one have an accident). I have been a bit nervous about relying on it for 100% of my charting needs, so I carry both for now, but frankly the IFly is way easier to use in my small cockpit than fumbling around with a bunch of charts which have to be folded and unfolded, etc. And I don't have to mark my intended route on the charts, which I used to do with removable colored tape. I may eventually drop my paper chart subscriptions, but for now they stay with me.
When ATC re-reroutes me, it has been much easier to "pull" the course over to the new routing with the IFly than pulling off tape and putting it elsewhere on the chart. I do not have an autopilot, so the less messing with charts, the better. The IFly was by far the least expensive option for electronic charts that I could find, and in my small cockpit, some of the larger options were simply not as practical as the IFly700 from a size standpoint, cost aside.
Incidentally the IFly, my 496, and my 430W have thus far agreed very closely regarding course and altitude. If there were any variation, I of course would rely on the 430W for nav, even in VFR. I fly near a lot of special use airspace, and the exceptional accuracy of the 430W is critical when near restricted and prohibited airspace.
In summary, so far I give the IFly a two thumbs up, and Walter has shown me excellent support.
Chris