As salam alaykum Dawud. I had some contact with Hizb-ut-tahrir during my time at university. positives; -raise awareness of khilafah -condemn and protest the killing and oppression of muslims whilst many are silent negatives; -I feel that some of the HT brothers have got their priorities wrong e.g more focus needs to be on raising iman and taqwa. -some can be very lenient in acting upon shariah e.g. clean shaven -aqeeda issues as mentioned by others. The danger in joining any islamic group without sound knowledge is that one can easily fall into ghuloo (exaggeration) and ta'assub (bias/bigotry) overall as with any other islamic group e.g Ikhwan al muslimeen, T.J e.t.c one should take from the good HT do and leave the bad. if they are doing something positive then inshallah co-operate whilst being cautious, aware of their mistakes and refraining from restricting the truth to 1 particular group.