I have already written quite a lot regarding the conceptual difficulties surrounding String Theory.
As it stands I would say that from a qualitative perspective, it presently does not constitute a meaningful physical interpretation of the Universe.
However once some of its key ideas are properly decoded we can begin to appreciate what it really is all about.
Conventional Science is heavily based on the linear rational approach which is thereby 1-dimensional in qualitative terms. This attempts to give one unambiguous direction to understanding e.g. interpretation that is (merely) objective, space distances that are (merely) positive, propositions that are (merely) true etc.
Not surprisingly - in terms of this approach - the most fundamental constituent of matter i.e. the string is viewed likewise as 1-dimensional in quantitative terms.
Common sense notions of the nature of space and time likewise reflect the 1-dimensional qualitative approach. Here we view 3 dimensions as spatial (with direct quantitative characteristics) and the remaining dimension in qualitative terms separated as time.
Now from a quantitative perspective, String Theory has to admit the existence of extra dimensions. So with its later incarnation in M-theory, we now have the inclusion of 7 extra dimensions (giving 11 in all). However a direct correspondence with the 1-dimensional qualitative approach is maintained through treating all of these extra dimensions in spatial terms (maintaining just 1-dimension in time).
So the very interpretation of extra dimensions - which has no intuitive resonance with common-sense understanding of space and time - is itself a product of a reduced level of qualitative understanding (that remains 1-dimensional).
The clear corollary here is that once we concede the need for extra dimensions to physical reality (from a quantitative perspective) equally we need to concede the need for extra dimensions also in terms of qualitative interpretation of this reality.
So the real message of String Theory is that the present (1-dimensional) scientific paradigm is no longer adequate for interpretation of the fundamenntal nature of physical reality.
Bearing this in mind I have already proposed that the very notion of a string must be given two complementary interpretations (in quantitative and qualitative terms).
So from the quantitative perspective, the fundamental building block is the 1-dimensional string which then through various dynamic vibration patterns, produces the physical particles.
Equally from the qualitative perspective, the fundamental building block is the 1-dimensional (holistic) string, which likewise through dynamic vibration patterns produces various psychological interpretations of these particles. Properly understood as phenomena and dimensions are quantitative and qualitative with respect to each other, these implies that we cannot properly hope to interpret the dimensional aspect of strings without incorporating the qualitative element.
And for proper intuitive recognition of what in physical terms String Theory entails, higher dimensional qualitative interpretations of reality will be clearly required.
In my own work such higher dimensional interpretations are provided through Integral Science.
For some 20 years now I have maintained the key importance of 8-dimensional qualitative interpretation for a comprehensive holistic TOE. Now it is hardly a coincidence that this thereby implies 7 extra dimensions of interpretation (in terms of the conventional approach) while M-theory itself likewise postulates 7 extra space dimensions in quantitative terms.
However once again because - from a qualitative perspective - String Theory remains rigidly rooted in a 1-dimensional interpretation, its quantitative findings can establish little or no resonance with common sense intuitions regarding the world.
There is another extremely important (hidden) dimension to this new understanding that can ultimately make the (quantitative) findings of String Theory intelligible. This is, relative to the quantitative aspect (which is interpreted analytically in dualistic terms), the qualitative aspect is appreciated holistically in nondual terms (which indirectly can be given an imaginary rational basis).
Thus seen in this light, String Theory is actually pointing to the fact that at its most fundamental, physical - which is now inseparable from psychological - reality corresponds to the operation of a dynamic interactive binary system (combining both analytic and holistic elements). So incorporated in this system are the means of both encoding (and decoding) all information and transformation processes.
So coming back to the string it now is given a complex interpretation in qualitative terms (as both real and imaginary)
Thus in terms of this definition, if the real aspect is identified with the quantitative aspect, the imaginary - by contrast - is then identified with the qualitative. And of course both of these aspects keep switching through dynamic interaction with each other.
Apart from this interaction, physical reality in its most fundamental manifestations has no strict meaning.
Put another way at this level we cannot hope to separate physical data (in quantitative terms) from the qualitative means through which they are interpreted.
Thus the ultimate nature of reality, in the resolution of this interaction of both quantitative and qualitative, is utterly ineffable (both beyond and preceding phenomenal investigation).
String Theory then stands as an opening physical bridge in terms of connecting what is empty and ineffable with the world of phenomenal form.