I've owned the ETX for a few weeks now and have been able to take it out 4 times so far (horrible weather

).
Here's my take on your questions:
What I like best about the scope is how accurate the goto is: the other night I decided to leave the 6.4mmEP in place (I purchased an extra EP for a bit more power) and it still managed to slew to the desired object and have it in the field of view. I was impressed! What I like least is probably the focusing...it takes a lot of turns when switching between the barlowed views and non barlowed views. I've read that an external barlow requires less focusing. (If you go that route, get a short barlow...I don't believe a long one will go in without hitting the angled mirror).

The motors are a bit noisy, especially when slewing. When tracking mine sounds like it is growling and burping.)

I have had a bit of slippage occasionally, but I just tighten and then realign (or just slew back to position if the slippage was slight). This has only happened twice in about 8 hours of logged viewing and only when the scope was pointed near horizontal.

Battery life is hard for me to judge...the first set of batteries lasted about 6 hours, but these were refugees from my digital camera (the camera had told me to replace them, but a battery tester showed them as still having about half of their capacity left). I started getting tracking errors with those batteries. I installed a fresh set (lithium AA this time) and it's more accurate then ever.

As far as optics, images appear fine to me...I can focus stars to points. There is some chromatic aberration, but not as bad as I was anticipating. (slight on Jupiter, a wire thin green ring around the Sun).

The focuser is a bit loose...I do wish it had a bit less play but you get used to it and adapt. It has been easy to focus regardless of declination or azmith. (Maybe just a tad harder when scope is vertical, but still doable...just takes more turns do to more limited turning travel).

I have the TC version...it comes with a somewhat heavier tripod then the backpack version. Tripod seems stable enough.

Some more observations: The scope does jump around a bit when focusing, but so does my Newtonian so I'm used to this. I have neve lost the image from the field of view...it does make focusing a bit more difficult, but just take your time and you will have things focused with less then a minute of effort. Tracking is less accurate when using the 6.4EP and barlow, but I haven't trained the drives yet. According to others, this improves tracking. So far, I just manually adjust every few seconds as I rarly use the scope at that power.
For the money, this scope is an excellent value. Consider that the included eyepieces sell for $39 dollars each...the autostar around $150, the tripod, I don't know but let's say $60 to be realistic. That's $288...plus you get a nice bag for the tripod...and the scope can be found for as low as $229 (Adorama...but they are out of stock just now). A very good deal in my book. If you go portable, I would also suggest getting the carrying case (or making your own) for the scope. Also, a dew cap is in order, as it is not included with the TC. I use an astrozap, but you could also make your own or buy the Meade cap.
Have fun!
Craig