I have been teaching Lingua Latina this year and I have met with some success. Not only are the students stronger readers, but they also claim that they like the text better than Ecce Romani. Their pronunciation has improved as well. I think it is the sheer amount of latin we read out loud in a week. I am also pleased with the College Companion for Lingua Latina as it has all the grammar explanations one could need. In the past I have recommended people use Lingua Latina with another textbook, but I think the College Companion is more than adequate.
I am using Lingua Latina I with a group of 7th/8th graders of average intelligence who progressed up until chapter 25 in Ecce Romani I last year. I do believe that Ecce Romani laid a good foundation for them to be able to read Lingua Latina. I think that they would struggle a lot more if they did not have the Ecce in their background. I also think that they like Latin being "easy" for the first quarter.
One of the reasons I was drawn to Lingua Latina (besides the 14 dollar price tag--Ecce is 75) is that I teach Latin to 5-8th graders for only one semester each year. It may happen that I teach 5th Latin in the Fall and not teach them again until Spring of their 6th grade year. I feel that Lingua Latina's format is conducive to this type of schedule, whereas I think it would be really difficult to pick up at Ecce Romani chapter 26, for example.
Anyway, my concerns with Lingua Latina are as follows: With all of the reading, it is really easy for a student to tune out and fall behind. If a student does not engage the text, Lingua Latina is no use. I have noticed that most can read the Latin really well (we are on Book eight) but that a few are already way behind. They stare at the ceiling the whole class and then ask what line we are on when called on. They then ask if Latin can send them to Summer School (sigh). I have not yet found a solution to this. The only workable solution would be for them to read the chapters on their own, but I am not holding my breath for that to happen.
I am still concerned that Lingua Latina gets too hard too fast, but we will see. I say that Book 10 is when I will start to notice some difficulties. However, I should add that the students did not freak when the passive was introduced in Chapter 6. Nor did they even blink when relative and demonstrative pronouns reared their heads in 7 and 8. So, maybe I am in for a pleasant surprise.
So my Latin plan right now is as follows: Ecce Romani for Latin 5 and Lingua Latina for Latin 6 and 7. I am not entirely satisfied with using Ecce Romani for half a year and then leaving it behind. I need to find a program that can be completed in a semester. I tried Minimus but found it too infantile.