The fixed expression “I must say” is used to give emphasis to a statement, usually regarding something positive or noteworthy. It is commonly used to express admiration, approval, or surprise. This phrase is often followed by adverbs such as “absolutely,” “extremely,” “pleasantly,” or conjunctions like “though,” and it can also incorporate more advanced vocabulary such as “impressed.” Overall, “I must say” is employed to highlight the speaker’s strong opinion or reaction to a particular situation or subject.

Here are three example sentences utilizing the given vocabulary:

1. “I must say, I am absolutely impressed with her performance. She showcased exceptional talent and stage presence.”
2. “The food at that restaurant was extremely delicious, I must say. Every dish we ordered was a pleasant surprise.”
3. “The weather may be cold, but the view from the top of the mountain is breathtaking, I must say. Though it was a challenging hike, the stunning scenery made it all worthwhile.”

Here’s an iWeb search for I must say * * * *

1 I MUST SAY THAT I AM VERY 144

EU-Startups

“Computer vision can have a big impact on the fashion …

I must say that I am very happy with how the complete team of Pixyle.ai adapted to working remotely. We were up and running from day 2.

2 I MUST SAY, THOUGH, THAT 93
3 I MUST SAY, HOWEVER, THAT 89
4 I MUST SAY I AM VERY IMPRESSED 82
5 I MUST SAY THAT I DON’T 75
6 I MUST SAY THAT I AM NOT 73
7 I MUST SAY THAT I WAS VERY 71
8 I MUST SAY YOU HAVE DONE A 68
9 I MUST SAY THAT I HAVE NEVER 66
10 I MUST SAY I WAS A LITTLE 63
11 I MUST SAY THIS IS ONE OF 61
12 I MUST SAY THAT THIS IS A 59
13 I MUST SAY I WAS VERY IMPRESSED 57
14 I MUST SAY THAT THIS IS THE 56
15 I MUST SAY THAT IT IS A 50
16 I MUST SAY I AM IMPRESSED . 49
17 I MUST SAY I AM VERY PLEASED 48
18 I MUST SAY I WAS PLEASANTLY SURPRISED 48

I must say I was pleasantly surprised by the sign language used 

when the Mazie and the Bird Girl Trio sang.

broadwayworld.com

19 I MUST SAY THAT IT WAS A 48
20 I MUST SAY THAT I HAVE BEEN 47
21 I MUST SAY, I AM VERY 46
22 I MUST SAY THAT YOU’VE DONE A 46
23 I MUST SAY THAT THIS IS ONE 45
24 I MUST SAY THIS IS THE BEST 45
25 I MUST SAY THAT I AM IMPRESSED 44
26 I MUST SAY I WAS A BIT 43
27 I MUST SAY THAT I AGREE WITH 43
28 I MUST SAY THAT I DON’T 42
29 I MUST SAY, IT ‘S A 41
30 I MUST SAY I AM IMPRESSED WITH 41
31 I MUST SAY I WAS IMPRESSED WITH 41
32 I MUST SAY THAT I DO NOT 41
33 I MUST SAY, IT WAS A 40
34 I MUST SAY, THIS IS A 40
35 I MUST SAY THAT I AM A 40
36 I MUST SAY THAT I LOVE THE 40
37 I MUST SAY, THIS IS THE 39
38 I MUST SAY, I DON’T 38
39 I MUST SAY, I WAS VERY 36
40 I MUST SAY I’M VERY IMPRESSED 36
41 I MUST SAY THAT I LIKE THE 36
42 I MUST SAY, IT IS A 33
43 I MUST SAY I AM VERY HAPPY 33
44 I MUST SAY IT WAS HARD TO 33
45 I MUST SAY THAT I WAS A 32
46 I MUST SAY, I WAS A 31
47 I MUST SAY, I’M VERY 30
48 I MUST SAY THAT I’M VERY 30
49 I MUST SAY THAT I AM EXTREMELY 30
50 I MUST SAY THAT IT HAS BEEN 30
51 I MUST SAY THAT I AM REALLY 29
52 I MUST SAY I’M IMPRESSED . 28
53 I MUST SAY THAT I ‘M NOT 28
54 I MUST SAY, I’M NOT 27
55 I MUST SAY, I HAVE BEEN 27
56 I MUST SAY I’M A LITTLE 27
57 I MUST SAY I LOVE IT . 27
58 I MUST SAY THAT I ABSOLUTELY LOVE 27
59 I MUST SAY, I AM NOT 26
60 I MUST SAY, I DON’T 26
61 I MUST SAY. 25
62 I MUST SAY I AM QUITE IMPRESSED 25
63 I MUST SAY THAT I HAVE NOT 25
64 I MUST SAY THIS IS A GREAT 25
65 I MUST SAY, I AM IMPRESSED 24
66 I MUST SAY, I LOVE IT 24
67 I MUST SAY, THIS IS ONE 24
68 I MUST SAY I AM A BIT 24
69 I MUST SAY I AM A LITTLE 24
70 I MUST SAY THAT I AM QUITE 24
71 I MUST SAY THAT I WAS PLEASANTLY 24
72 I MUST SAY I LOVE IT ! 23
73 I MUST SAY IT WAS A GREAT 23
74 I MUST SAY THAT I ‘M IMPRESSED 23
75 I MUST SAY THAT I FIND IT 23
76 I MUST SAY THAT I REALLY LIKE 22
77 I MUST SAY THAT I WAS IMPRESSED 22
78 I MUST SAY THAT IT IS THE 22
79 I MUST SAY, I AM A 21
80 I MUST SAY, I DIDN’T 21
81 I MUST SAY A BIG THANK YOU 21
82 I MUST SAY I’M VERY HAPPY 21
83 I MUST SAY IT IS THE BEST 21
84 I MUST SAY THAT I AM SO 21
85 I MUST SAY THAT I DID NOT 21
86 I MUST SAY THAT I HAVE A 21
87 I MUST SAY THAT I WAS NOT 21
88 I MUST SAY THAT I WAS QUITE 21
89 I MUST SAY THAT IT ‘S A 21
90 I MUST SAY THAT IT IS VERY 21
91 I MUST SAY THIS IS A VERY 21
92 I MUST SAY, I’M A 20
93 I MUST SAY IT IS ONE OF 20
94 I MUST SAY THAT I AM SURPRISED 20
95 I MUST SAY THAT I CAN NOT 20
96 I MUST SAY THAT I WAS SURPRISED 20
97 I MUST SAY, I HAVE NEVER 19
98 I MUST SAY, I LOVE THE 19
99 I MUST SAY, I REALLY LIKE 19
100 I MUST SAY, I WAS IMPRESSED 19

B1 vocabulary in the above lines:

absolutely, extremely, pleasantly, though
B2:
impressed