Telling What We or Other People Think of Something

1. Asking for Opinions
    "Do you have any views on … ?"

This page lists useful expressions for the language function of asking for opinions.
 
Elementary
    Do you think … ?
    How do you feel about … ?
    In your opinion, … ?
    Please tell me your opinion on …
    What do you think about … ?
    What’s your opinion on … ?

Pre-intermediate
    Do you (also) think that … ?
    Do you believe that … ?
    Do you have an opinion on … ?
    Do you have any opinions on/about … ?
    In your experience, … ?
    In your honest opinion, … ?
    What’s your view on … ?
    Would you agree that … ?

Intermediate
    Can you give me your thoughts on … ?
    Do you (dis)approve of … ?
    Do you agree with the opinion that … ?
    Do you have any views on … ?
    Do you share the/my view that … ?
    If I asked your opinion about … , … ?
    If I said … , … ?
    I’d like (to hear) your views on …
    I’m sure you’d agree that …
    What are your feelings about … ?
    What are your views on … ?

Upper-intermediate
    What do you reckon?
    Any (initial) thoughts on … ?
    Are people right in thinking … ?
    Are you in agreement with … ?
    Do you have any particular views on … ?
    Do you have any thoughts on … ?
    From your point of view, … ?
    I know this is not your specialist subject, but …
    I know you haven’t had long to think about this …
    I know you haven’t had much time to think about this, but …
    I’d be (very) interested to hear your views on …
    What are your (first) thoughts on … ?
    What would be your reaction if I said … ?
    What’s your position on … ?
    Would it be right to say … ?
    Would you support the view that … ?

Advanced

    Am I justified in saying … ?
    Am I right in thinking … ?
    Any objections to the statement … ?
    Are you convinced by the argument that … ?
    Are you of the opinion that … ?
    Does … tally with your experience?
    I imagine you will have strong opinions on …
    I’d guess your view on this is …
    Is it in fact the case that … ?
    What reaction do you have to … ?
    What’s your take on … ?
    Would I be right in assuming that you think … ?
    Would I be right in saying … ?
    Would I/it be wrong to say … ?
    Would it be logical to say … ?
    Would you have any problems with the statement … ?
    Would … be a fair summary of your views on … ?
    Would … be out of the question?
    You strike me as someone who would hold the opinion that …

2. Giving Opinions
    This is just my opinion, but...

This page lists useful expressions for the language function of giving opinions.
 
Elementary
    I (really) think that …
    I believe (that) …
    I’m sure that …
    In my opinion / My opinion is …

Pre-intermediate
    I agree with …
    I feel that …
    I guess/imagine …
    I have no doubt that / I’m certain that …
    I strongly believe that …
    I’ve never really thought about this before, but …
    My personal opinion is that / Personally, my opinion is that …
    To be honest / In my honest opinion, …

Intermediate
    As far as I know, …
    I agree with the opinion of …
    I could be wrong, but …
    I’d definitely say that …
    I’d guess/imagine that …
    I’d say that …
    I’m absolutely certain that …
    I’m fairly confident that …
    I’m no expert (on this), but …
    I’m positive that …
    I’m pretty sure that …
    It seems to me that …
    It’s a complicated/difficult issue, but …
    My (point of) view (on this) is …
    Obviously, …
    Some people may disagree with me, but …
    This is just my opinion, but …
    Without a doubt, …
    You probably won’t agree, but …

Upper-intermediate
    After much thought, …
    After weighing up both sides of the argument, …
    Although I can see both points of view / Although I can understand the opposite point of view, …
    As I see it, ...
    Correct me if I’m wrong, but …
    For me/ From my point of view, …
    Frankly, …
    I am not very familiar with this topic, but …
    I do believe/ feel/think …
    I have come to the conclusion that …
    I might change my mind later, but …
    I reckon/suppose …
    I tend to think that …
    I’m not sure I’m the right person to ask, but / I have very limited experience of this, but …
    I’m pretty confident that …
    I’ve always thought that …
    If you ask me, …
    I'm (absolutely) convinced that …
    In my humble opinion / IMHO, …
    It could be said that …
    It seems clear to me that …
    It would seem to me that …
    My initial reaction is …
    Not everyone will/would agree with me, but …
    Personally speaking / Speaking for myself, …
    The way I see it (is) …
    To be (perfectly) frank, …
    To the best of my knowledge, …
    What I think is …
    You could say …

Advanced
    After giving this matter some (serious) thought, …
    As far as I'm concerned, …
    As the old saying goes, …
    Having given this question due consideration, …
    I am of the opinion that …
    I can’t help thinking that …
    I know this is a minority view, but / I’m in the minority in thinking that …
    I tend towards the opinion that …
    I think it’s fair/reasonable to say …
    I’ll tell you what I think, …
    I’m entirely/quite convinced that …
    I’ve come the conclusion that …
    If I must come up with an opinion / If you (really) want my opinion, …
    In my limited experience, …
    It could/might well be that …
    Know what I think? …
    My opinion was best expressed by … when s/he said/wrote …
    My view/position on this (issue) (is clear and) is that …
    Off the top of my head, …
    Plainly, …
    Quite frankly, …
    There is a part of me that says …
    This may well be controversial, but …
    To my mind / To my way of thinking, ...
    To summarise my (rather complex) views on the matter, …
    What I always say is …
    With some reservations, …
    Without a shred/shadow of doubt, …
    You’d have to be crazy not to agree that / Any idiot can see that …

Source: damaruta.com from englishclub.com