However, I see on the forum issues with sheevaplug too, which as far as I'm aware is one of the few rivals. Oh well!
It seems most of the problems with the SheevaPlug were with the poor capacitors in the original power supplies. GlobalTech claims that they have a new supplier. I received a Sheeva in 2010/12 (in the U.S.) with a new-style PSU, so am able to confirm that at least some of the current deliveries are with the new PSUs.
The problems with the Sheeva seem to have declined more recently, so it appears that the new PSUs have been an improvement. However, there are still a few occasional complaints. As with the first wave, this seems to be associated with usage on 240V mains power or with an unpowered USB device.
So, regrettably, it does not seem to have been categorically proven that the PSU, even in the Sheeva, is adequate for long-term use for the purposes that many on the site intend for their Plugs.
The general heating situation with the Sheeva has always been (reported to be) better than the Guru. In my experience, when doing a large software build (30 minutes of compiling and linking), the plastic case would still get warmer than I was comfortable with. (Keeping in mind, this is radiant
heat from the heat-spreading plate jumping the air gap to the plastic case, so the cpu was running hotter.)
In my opinion, these devices suffer from the same limitation that apply to most consumer goods these days -- they were not designed with long-term use in mind. (As we all know, in general, the hotter electronic components run, the more likely a failure will occur, sooner.) Could be planned obsolescence, could be "Make it cheap, and get it out the door."
That all being said, if one can look past the issues like the PSU, the problems with the mini-USB connector or SD card slot on individual units, the main board seems to be adequate.
It may be extreme, but my recommendation for many of these small devices would be 1) select a device with a lower-powers cpu, or 2) expect to replace it, or 3) re-house the board in some other other box, with a decent heat-sink.
My choice was an external PSU and re-housing the board in a metal box, with a (large) heat sink from the plate to the box. For my purposes, the cost savings (reduced telephone bill) will recoup the costs of the mods in a month or two. Obviously, others will make their own decisions based upon their needs and wants.