The main criticism is directed to the formal presentation of the theory (heavy mathematical jargon), number of listed parameters, the symbol heavy notation, and the fact that modeled (state) variables and parameters are abstract quantities which cannot be directly measured, all making it less likely to reach its intended audience (ecologists) and be an "efficient" theory.
However, more recent publications aim to present the DEB theory in an "easier to digest" content to "bridge the ecology-mathematics gap". List of parameters is a direct result of list of processes which are of interest—if only growth under constant food and temperature is of interest, the standard DEB model can be simplified to the von Bertalanffy growth curve. Adding more processes into focus (such as reproduction and/or maturation), and forcing the model with fluctuating (dynamic) environmental conditions, needless to say, will result in more parameters.
The general methodology of estimation of DEB parameters from data is described in [http://www.bio.vu.nl/thb/research/bib/Meer2006.html van der Meer 2006]; [http://www.bio.vu.nl/thb/research/bib/KooySous2008.html Kooijman et al 2008] shows which particular compound parameters can be estimated from a few simple observations at a single food density and how an increasing number of parameters can be estimated if more quantities are observed at several food densities. A natural sequence exists in which parameters can be known in principle. In addition, routines for data entry and scripts for parameter estimation are available as a free and documented software package [http://www.bio.vu.nl/thb/deb/deblab/debtool/DEBtool_M/manual/index.html DEBtool] , aiming to provide a ready-to-use tool for users with less mathematical and programing background. Number of parameters, also pointed as relatively sparse for a bioenergetic model, vary depending on the main application and, because the whole life cycle of an organism is defined, the overall number of parameters per data-set ratio is relatively low. Linking the DEB (abstract) and measured properties is done by simple mathematical operations which include auxiliary parameters (also defined by the DEB theory and included in the [http://www.bio.vu.nl/thb/deb/deblab/debtool/DEBtool_M/manual/index.html DEBtool]  routines), and include also switching between energy-time and mass-time contexts.  [https://www.bio.vu.nl/thb/deb/deblab/add_my_pet/index.html Add my pet (AmP)] project explores parameter pattern values across taxa. The DEB notation is a result of combining the symbols from the main fields of science (biology, chemistry, physics, mathematics) used in the theory, while trying to keep the symbols consistent. As the symbols themselves contain a fair bit of information   (see [http://www.bio.vu.nl/thb/research/bib/Kooy2010_n.pdf DEB notation] document), they are kept in most of the DEB literature.