My experience has been about the same. I really can't understand why so many people are so enamored with these things.
You really have to work on it to get these to work properly. I will admit when I first started using these I was not impressed. But now they are my favorite... I will explain in my response to Adik Ted
Very disappointed in these. I bought 5 and usage went as follows
1) A lot of spillage filling it but I must have managed to get a fair bit of it where it was supposed to go because I got about 8 hours of solid vaping with good draws, taste and throat hit. When I refilled it (again a lot of spillage) I got only a few minutes out of it before getting a burnt taste. I thought the cartomiser was done and ruined it trying to take it apart to see how it work. After starting this thread I realised I probably hadn't filled it properly.
2) Managed to get it filled after reading Nick and Papa's posts. Decent draw but ruined by burnt taste from outset.
3) Filled this one properly (no leakage) but draw and vapour were weak and again had the burnt taste.
4) Dry burnt this one as per Papa's suggestion. As I was using an automatic I blew on the led end to fire it up (some smoke did come from other end). Again filled this one properly with no leakage but got about 5 decent draws out of it before it vaped as if it was empty.
5) Tried this one without dry burn. Stuck with the burnt taste again and again draw seems weak.
If I was new to vaping I'd be back on the tobacco by now.
1) Your filling problems probably are the same as mine. I would inject until I saw liquid pool up over the cup. That is too much. Do it just enough to come out of the hole on the other side (you will see it bubble). Personally, I took that plug completely out and replaced it with a regular inner plug from a cheap plastic tipped chinese carto so I can pop all 3 out and just fill like a regular carto. With that method I recommend an empty 510 cart on top instead of the regular plug to prevent leakage. With the cart I haven't had leaking problems. If your juice is burning quickly you should try a PG heavy mix. The juice I use is 2/3 PG 1/3 VG and it wicks just fine. Also what voltage are you using? if it is 3.7-4.2 a 2.5 ohm ce2 should be good. 4.3-5v you should use a 2.8ohm. anything higher than that get a 3.0-3.2 ohm (all available at COV).
*EDIT*
I DO NOT recommend these for higher than 6v. Trust me lol. They have to come out with at least a 3.5ohm before they can be used at 7.4v.
2) Once my ce2s develop a burnt taste (they rarely do) I always rinse with hot water, dry burn, blow the gunk off, rinse with hot water, and dry burn again. Without doing this, the ce2 will retain its burnt flavor.
3) Was this a fresh one? if so you should really use the method I mentioned in 2) prior to use (these have some weird chemical taste off the bat probably from the wick)
4) Dry burning with auto batteries will be very difficult. But you have to dry burn until coils are bright red and virtually no smoke is coming out. I recommend no higher than 3.7v to dry burn the 2.5-2.8ohm ce2s 5v for higher. And it is much easier with a manual battery (vaping is better with a manual too

).
5) Using one without a dry burn is always nasty. It is an absolute must.
Hope this helped guys!