It always says "You can add images once you have saved for the first time." but from backed it is ok. all other fields works properly. Please help!
this is for frontend:

	
function addHotelForm(){                               
    return new Form($this, "addHotelForm",
        new FieldSet(
			new TextField('Title', 'Название'),
            new TextareaField('Description', 'Описание'),
            new TextField('Location', 'Местоположение'),  
			new TextField('Adress', 'Адрес'),
			new TextField('Telefone', 'Телефон'),
			new NumericField('Price', 'Цены'),
			new ImageField('HotelImage', 'Фото Гостиннцы', null, null, null, "assets/Uploads/")
        ),
        new FieldSet(
            new FormAction("doSubmitHotel", "добавить новую гостинницу")
        ), 
		new RequiredFields(
            'Description'
		)	
    );
}

function doSubmitHotel($data, $form){
		$hotel = new Hotel();
		$form->saveInto($hotel);
		$hotel->HotelHolderID = $this->dataRecord->ID;
		$hotel->write();
		$form->sessionMessage(
			'Гостинница успешно добавлена!',
			'good'
		);
		Director::redirectBack();
		return;
}

and for CMS:

	
function getCMSFields() {
	$fields = parent::getCMSFields();
	$HotelTable = new ComplexTableField($this, 'Hotels', 'Hotel');
	$fields->addFieldToTab('Root.Content.Hotels', $HotelTable);
	return $fields;
}

the "assets/Uploads/" don't work too, images saved to Uploads folder

You should use SimpleImageField for the front end form. The incorrect folder location I think was a bug in 2.3 which should be fixed in 2.4.

Thanks Willr